diff --git a/schema.graphqls b/schema.graphqls
index 614bfa0..b37b8d4 100644
--- a/schema.graphqls
+++ b/schema.graphqls
@@ -1,3 +1,5 @@
+scalar DateTime
+
 # The Interchange system schema.
 # Note how Passio ID and parking ID are abstracted away
 # from the endpoints.
@@ -27,6 +29,7 @@ type ParkingStructure {
   spotsAvailable: Int!
   coordinates: Coordinates!
   address: String!
+  updatedTime: DateTime
 }
 
 type Route {
@@ -37,6 +40,7 @@ type Route {
   shuttles: [Shuttle!]
   polylineCoordinates: [Coordinates!]!
   color: String!
+  updatedTime: DateTime
 }
 
 type OrderedStop {
@@ -47,6 +51,7 @@ type OrderedStop {
   stop: Stop
   stopId: ID!
   systemId: ID!
+  updatedTime: DateTime
 }
 
 type Stop {
@@ -56,6 +61,7 @@ type Stop {
   coordinates: Coordinates!
   etas: [ETA!]
   orderedStops: [OrderedStop!]
+  updatedTime: DateTime
 }
 
 type Coordinates {
@@ -70,6 +76,7 @@ type ETA {
   shuttleId: ID!
   secondsRemaining: Float!
   systemId: ID!
+  updatedTime: DateTime
 }
 
 type Shuttle {
@@ -82,6 +89,7 @@ type Shuttle {
   etas: [ETA!]
   eta(forStopId: ID): ETA
   orientationInDegrees: Float!
+  updatedTime: DateTime
 }
 
 # Queries
diff --git a/src/MergedResolvers.ts b/src/MergedResolvers.ts
index 795ec38..c1925ff 100644
--- a/src/MergedResolvers.ts
+++ b/src/MergedResolvers.ts
@@ -1,4 +1,4 @@
-import { Coordinates, Eta, OrderedStop, Resolvers } from "./generated/graphql";
+import { Resolvers } from "./generated/graphql";
 import { ServerContext } from "./ServerContext";
 import { QueryResolvers } from "./resolvers/QueryResolvers";
 import { SystemResolvers } from "./resolvers/SystemResolvers";
@@ -9,6 +9,7 @@ import { ShuttleResolvers } from "./resolvers/ShuttleResolvers";
 import { RouteResolvers } from "./resolvers/RouteResolvers";
 import { MutationResolvers } from "./resolvers/MutationResolvers";
 import { ParkingSystemResolvers } from "./resolvers/ParkingSystemResolvers";
+import { DateTime } from "./scalars/DateTime";
 
 export const MergedResolvers: Resolvers<ServerContext> = {
   ...QueryResolvers,
@@ -20,4 +21,5 @@ export const MergedResolvers: Resolvers<ServerContext> = {
   ...OrderedStopResolvers,
   ...EtaResolvers,
   ...MutationResolvers,
+  DateTime: DateTime,
 };
diff --git a/src/entities/ParkingRepositoryEntities.ts b/src/entities/ParkingRepositoryEntities.ts
index f0dadea..b78a754 100644
--- a/src/entities/ParkingRepositoryEntities.ts
+++ b/src/entities/ParkingRepositoryEntities.ts
@@ -1,6 +1,6 @@
-import { ICoordinates, IEntityWithId, IEntityWithOptionalTimestamp } from "./SharedEntities";
+import { ICoordinates, IEntityWithId, IEntityWithTimestamp } from "./SharedEntities";
 
-export interface IParkingStructure extends IEntityWithOptionalTimestamp, IEntityWithId {
+export interface IParkingStructure extends IEntityWithTimestamp, IEntityWithId {
   address: string;
   capacity: number;
   spotsAvailable: number;
diff --git a/src/entities/SharedEntities.ts b/src/entities/SharedEntities.ts
index ad723c5..67aa03e 100644
--- a/src/entities/SharedEntities.ts
+++ b/src/entities/SharedEntities.ts
@@ -1,5 +1,5 @@
-export interface IEntityWithOptionalTimestamp {
-  millisecondsSinceEpoch?: number;
+export interface IEntityWithTimestamp {
+  updatedTime: Date;
 }
 
 export interface IEntityWithId {
diff --git a/src/entities/ShuttleRepositoryEntities.ts b/src/entities/ShuttleRepositoryEntities.ts
index 3ab9a29..608bda6 100644
--- a/src/entities/ShuttleRepositoryEntities.ts
+++ b/src/entities/ShuttleRepositoryEntities.ts
@@ -1,19 +1,19 @@
-import { ICoordinates, IEntityWithId, IEntityWithOptionalTimestamp } from "./SharedEntities";
+import { ICoordinates, IEntityWithId, IEntityWithTimestamp } from "./SharedEntities";
 
-export interface IRoute extends IEntityWithId, IEntityWithOptionalTimestamp {
+export interface IRoute extends IEntityWithId, IEntityWithTimestamp {
   name: string;
   color: string;
   polylineCoordinates: ICoordinates[];
   systemId: string;
 }
 
-export interface IStop extends IEntityWithId, IEntityWithOptionalTimestamp {
+export interface IStop extends IEntityWithId, IEntityWithTimestamp {
   name: string;
   systemId: string;
   coordinates: ICoordinates;
 }
 
-export interface IShuttle extends IEntityWithId, IEntityWithOptionalTimestamp {
+export interface IShuttle extends IEntityWithId, IEntityWithTimestamp {
   coordinates: ICoordinates;
   name: string;
   routeId: string;
@@ -21,14 +21,14 @@ export interface IShuttle extends IEntityWithId, IEntityWithOptionalTimestamp {
   orientationInDegrees: number;
 }
 
-export interface IEta extends IEntityWithOptionalTimestamp {
+export interface IEta extends IEntityWithTimestamp {
   secondsRemaining: number;
   shuttleId: string;
   stopId: string;
   systemId: string;
 }
 
-export interface IOrderedStop extends IEntityWithOptionalTimestamp {
+export interface IOrderedStop extends IEntityWithTimestamp {
   nextStop?: IOrderedStop;
   previousStop?: IOrderedStop;
   routeId: string;
diff --git a/src/loaders/parking/ChapmanApiBasedParkingRepositoryLoader.ts b/src/loaders/parking/ChapmanApiBasedParkingRepositoryLoader.ts
index 9730df8..5cfafea 100644
--- a/src/loaders/parking/ChapmanApiBasedParkingRepositoryLoader.ts
+++ b/src/loaders/parking/ChapmanApiBasedParkingRepositoryLoader.ts
@@ -58,7 +58,8 @@ export class ChapmanApiBasedParkingRepositoryLoader implements ParkingRepository
       id: ChapmanApiBasedParkingRepositoryLoader.generateId(jsonStructure.Address),
       name: jsonStructure.Name,
       spotsAvailable: jsonStructure.CurrentCount > jsonStructure.Capacity ? jsonStructure.Capacity : jsonStructure.CurrentCount,
-      address: jsonStructure.Address
+      address: jsonStructure.Address,
+      updatedTime: new Date(),
     }
 
     return structureToReturn;
diff --git a/src/loaders/parking/loadParkingTestData.ts b/src/loaders/parking/loadParkingTestData.ts
index f73d15a..be7663d 100644
--- a/src/loaders/parking/loadParkingTestData.ts
+++ b/src/loaders/parking/loadParkingTestData.ts
@@ -12,6 +12,7 @@ const parkingStructures: IParkingStructure[] = [
     },
     name: "Anderson Structure",
     id: "1",
+    updatedTime: new Date(),
   },
   {
     address: "200 W Sycamore Ave, Orange, CA 92866-1053",
@@ -23,6 +24,7 @@ const parkingStructures: IParkingStructure[] = [
     },
     name: "Barrera",
     id: "2",
+    updatedTime: new Date(),
   }
 ];
 
diff --git a/src/loaders/shuttle/ApiBasedShuttleRepositoryLoader.ts b/src/loaders/shuttle/ApiBasedShuttleRepositoryLoader.ts
index 062ff43..c7735aa 100644
--- a/src/loaders/shuttle/ApiBasedShuttleRepositoryLoader.ts
+++ b/src/loaders/shuttle/ApiBasedShuttleRepositoryLoader.ts
@@ -73,6 +73,7 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
             id: jsonRoute.myid,
             polylineCoordinates: [],
             systemId: this.systemIdForConstructedData,
+            updatedTime: new Date(),
           };
 
           await this.repository.addOrUpdateRoute(constructedRoute);
@@ -172,7 +173,8 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
             routeId: jsonBus.routeId,
             systemId: this.systemIdForConstructedData,
             id: `${jsonBus.busId}`,
-            orientationInDegrees: parseFloat(jsonBus.calculatedCourse)
+            orientationInDegrees: parseFloat(jsonBus.calculatedCourse),
+            updatedTime: new Date(),
           }
 
           await this.repository.addOrUpdateShuttle(constructedShuttle);
@@ -221,7 +223,7 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
             secondsRemaining: jsonEta.secondsSpent,
             shuttleId: `${shuttleId}`,
             stopId: stopId,
-            millisecondsSinceEpoch: Date.now(),
+            updatedTime: new Date(),
             systemId: this.systemIdForConstructedData,
           };
 
@@ -249,6 +251,7 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
             latitude: parseFloat(stop.latitude),
             longitude: parseFloat(stop.longitude),
           },
+          updatedTime: new Date(),
         };
 
         await this.repository.addOrUpdateStop(constructedStop);
@@ -280,6 +283,7 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
               stopId,
               position: index + 1,
               systemId: this.systemIdForConstructedData,
+              updatedTime: new Date(),
             };
           }
 
@@ -289,6 +293,7 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
               stopId: jsonOrderedStopData[index - 1][1],
               position: index,
               systemId: this.systemIdForConstructedData,
+              updatedTime: new Date(),
             };
           }
           if (index < jsonOrderedStopData.length - 1) {
@@ -297,6 +302,7 @@ export class ApiBasedShuttleRepositoryLoader implements ShuttleRepositoryLoader
               stopId: jsonOrderedStopData[index + 1][1],
               position: index + 2,
               systemId: this.systemIdForConstructedData,
+              updatedTime: new Date(),
             };
           }
 
diff --git a/src/loaders/shuttle/loadShuttleTestData.ts b/src/loaders/shuttle/loadShuttleTestData.ts
index c0c4e63..782962d 100644
--- a/src/loaders/shuttle/loadShuttleTestData.ts
+++ b/src/loaders/shuttle/loadShuttleTestData.ts
@@ -4324,6 +4324,7 @@ const routes: IRoute[] = [
     systemId: supportedIntegrationTestSystems[0].id,
     polylineCoordinates: redRoutePolylineCoordinates,
     color: "#db2316",
+    updatedTime: new Date(),
   },
   {
     name: "Teal Route",
@@ -4331,6 +4332,7 @@ const routes: IRoute[] = [
     systemId: supportedIntegrationTestSystems[0].id,
     polylineCoordinates: tealRoutePolylineCoordinates,
     color: "#21bdd1",
+    updatedTime: new Date(),
   },
 ];
 
@@ -4343,6 +4345,7 @@ const stops: IStop[] = [
       longitude: -117.8892805,
     },
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     id: "2",
@@ -4352,6 +4355,7 @@ const stops: IStop[] = [
       longitude: -117.895966,
     },
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     id: "3",
@@ -4361,6 +4365,7 @@ const stops: IStop[] = [
       "longitude": -117.85281
     },
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   }
 ];
 
@@ -4370,12 +4375,14 @@ const orderedStopsForRedRoute: IOrderedStop[] = [
     stopId: stops[0].id,
     position: 1,
     systemId: "1",
+    updatedTime: new Date(),
   },
   {
     routeId: routes[0].id,
     stopId: stops[2].id,
     position: 2,
     systemId: "1",
+    updatedTime: new Date(),
   },
 ];
 
@@ -4385,18 +4392,21 @@ const orderedStopsForTealRoute: IOrderedStop[] = [
     stopId: stops[0].id,
     position: 1,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     routeId: routes[1].id,
     stopId: stops[1].id,
     position: 2,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     routeId: routes[1].id,
     stopId: stops[2].id,
     position: 2,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
 ]
 
@@ -4416,6 +4426,7 @@ const shuttles: IShuttle[] = [
     routeId: routes[0].id,
     systemId: supportedIntegrationTestSystems[0].id,
     orientationInDegrees: 45.91,
+    updatedTime: new Date(),
   },
   {
     name: "24",
@@ -4427,6 +4438,7 @@ const shuttles: IShuttle[] = [
     routeId: routes[0].id,
     systemId: supportedIntegrationTestSystems[0].id,
     orientationInDegrees: 90.24,
+    updatedTime: new Date(),
   }
 ];
 
@@ -4436,24 +4448,28 @@ const etas: IEta[] = [
     shuttleId: shuttles[0].id,
     secondsRemaining: 12.023,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     stopId: stops[2].id,
     shuttleId: shuttles[0].id,
     secondsRemaining: 600.123,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     stopId: stops[2].id,
     shuttleId: shuttles[1].id,
     secondsRemaining: 172.015,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   },
   {
     stopId: stops[0].id,
     shuttleId: shuttles[1].id,
     secondsRemaining: 710.152,
     systemId: supportedIntegrationTestSystems[0].id,
+    updatedTime: new Date(),
   }
 ];
 
diff --git a/src/resolvers/OrderedStopResolvers.ts b/src/resolvers/OrderedStopResolvers.ts
index 0410e46..54ae00a 100644
--- a/src/resolvers/OrderedStopResolvers.ts
+++ b/src/resolvers/OrderedStopResolvers.ts
@@ -24,6 +24,7 @@ export const OrderedStopResolvers: Resolvers<ServerContext> = {
         routeId: parent.routeId,
         stopId: nextOrderedStopObject.id,
         systemId: system.id,
+        updatedTime: nextOrderedStopObject.updatedTime
       }
     },
     previousStop: async (parent, args, contextValue, _info): Promise<OrderedStop | null> => {
@@ -47,6 +48,7 @@ export const OrderedStopResolvers: Resolvers<ServerContext> = {
         routeId: parent.routeId,
         stopId: previousOrderedStopObject.id,
         systemId: system.id,
+        updatedTime: previousOrderedStopObject.updatedTime,
       }
     },
     stop: async (parent, args, contextValue, _info) => {
diff --git a/src/resolvers/RouteResolvers.ts b/src/resolvers/RouteResolvers.ts
index aa29fdc..43f6c53 100644
--- a/src/resolvers/RouteResolvers.ts
+++ b/src/resolvers/RouteResolvers.ts
@@ -3,7 +3,7 @@ import { ServerContext } from "../ServerContext";
 
 export const RouteResolvers: Resolvers<ServerContext> = {
   Route: {
-    shuttles: async (parent, args, contextValue, info) => {
+    shuttles: async (parent, args, contextValue, _info) => {
       const system = contextValue.findSystemById(parent.systemId);
       if (!system) return null;
 
@@ -13,7 +13,8 @@ export const RouteResolvers: Resolvers<ServerContext> = {
         coordinates,
         name,
         id,
-        orientationInDegrees
+        orientationInDegrees,
+        updatedTime
       }) => ({
         coordinates: coordinates as Coordinates,
         name,
@@ -22,9 +23,10 @@ export const RouteResolvers: Resolvers<ServerContext> = {
         id,
         orientationInDegrees,
         systemId: parent.systemId,
+        updatedTime,
       }));
     },
-    orderedStop: async (parent, args, contextValue, info) => {
+    orderedStop: async (parent, args, contextValue, _info) => {
       if (!args.forStopId) return null;
 
       const system = contextValue.findSystemById(parent.systemId);
@@ -41,6 +43,7 @@ export const RouteResolvers: Resolvers<ServerContext> = {
         routeId: parent.id,
         route: parent,
         systemId: system.id,
+        updatedTimeMs: orderedStop.updatedTime,
       }
     },
   },
diff --git a/src/resolvers/ShuttleResolvers.ts b/src/resolvers/ShuttleResolvers.ts
index 103e40f..2eb9478 100644
--- a/src/resolvers/ShuttleResolvers.ts
+++ b/src/resolvers/ShuttleResolvers.ts
@@ -18,6 +18,7 @@ export const ShuttleResolvers: Resolvers<ServerContext> = {
         shuttleId: parent.id,
         shuttle: parent,
         systemId: system.id,
+        updatedTimeMs: etaForStopId.updatedTime,
       };
     },
     etas: async (parent, args, contextValue, info) => {
@@ -27,17 +28,20 @@ export const ShuttleResolvers: Resolvers<ServerContext> = {
       const etasForShuttle = await system.shuttleRepository.getEtasForShuttleId(parent.id);
       if (!etasForShuttle) return null;
 
-      const computedEtas = await Promise.all(etasForShuttle.map(async ({
-                                                                         secondsRemaining,
-                                                                         stopId,
-                                                                       }): Promise<Eta | null> => {
-        return {
+      const computedEtas = await Promise.all(
+        etasForShuttle.map(async ({
           secondsRemaining,
           stopId,
-          shuttle: parent,
-          shuttleId: parent.id,
-          systemId: system.id,
-        }
+          updatedTime
+        }): Promise<Eta | null> => {
+          return {
+            secondsRemaining,
+            stopId,
+            shuttle: parent,
+            shuttleId: parent.id,
+            systemId: system.id,
+            updatedTime: updatedTime,
+          }
       }));
 
       if (computedEtas.every((eta) => eta !== null)) {
@@ -59,6 +63,7 @@ export const ShuttleResolvers: Resolvers<ServerContext> = {
         name: route.name,
         polylineCoordinates: route.polylineCoordinates,
         systemId: system.id,
+        updatedTimeMs: route.updatedTime
       }
     }
   },
diff --git a/src/resolvers/SystemResolvers.ts b/src/resolvers/SystemResolvers.ts
index dc10fe9..a955fc2 100644
--- a/src/resolvers/SystemResolvers.ts
+++ b/src/resolvers/SystemResolvers.ts
@@ -36,6 +36,7 @@ export const SystemResolvers: Resolvers<ServerContext> = {
         name: stop.name,
         coordinates: stop.coordinates as Coordinates,
         systemId: parent.id,
+        updatedTimeMs: stop.updatedTime,
       };
     },
     route: async (parent, args, contextValue, _info) => {
@@ -55,6 +56,7 @@ export const SystemResolvers: Resolvers<ServerContext> = {
         name: route.name,
         polylineCoordinates: route.polylineCoordinates as Coordinates[],
         systemId: parent.id,
+        updatedTimeMs: route.updatedTime,
       };
     },
     shuttle: async (parent, args, contextValue, _info) => {
diff --git a/src/scalars/DateTime.ts b/src/scalars/DateTime.ts
new file mode 100644
index 0000000..45a5ac6
--- /dev/null
+++ b/src/scalars/DateTime.ts
@@ -0,0 +1,28 @@
+import { GraphQLScalarType } from "graphql/type";
+import { Kind } from "graphql/language";
+
+// See Apollo documentation: https://www.apollographql.com/docs/apollo-server/schema/custom-scalars#providing-custom-scalars-to-apollo-server
+export const DateTime = new GraphQLScalarType({
+  name: 'DateTime',
+  description: 'DateTime custom scalar type',
+  serialize(value) {
+    if (value instanceof Date) {
+      return value.getTime();
+    } else if (value instanceof Number) {
+      return value;
+    }
+    throw Error('GraphQL Date Scalar serializer expected a `Date` object or number');
+  },
+  parseValue(value) {
+    if (typeof value === 'number') {
+      return new Date(value);
+    }
+    throw new Error('GraphQL Date Scalar parser expected a `number`');
+  },
+  parseLiteral(ast) {
+    if (ast.kind === Kind.INT) {
+      return new Date(parseInt(ast.value, 10));
+    }
+    return null;
+  },
+})
diff --git a/test/loaders/parking/ChapmanApiBasedParkingRepositoryLoaderTests.test.ts b/test/loaders/parking/ChapmanApiBasedParkingRepositoryLoaderTests.test.ts
index 9d9ebfc..ecd6a12 100644
--- a/test/loaders/parking/ChapmanApiBasedParkingRepositoryLoaderTests.test.ts
+++ b/test/loaders/parking/ChapmanApiBasedParkingRepositoryLoaderTests.test.ts
@@ -59,6 +59,7 @@ describe("ChapmanApiBasedParkingRepositoryLoader", () => {
           },
           name: "Anderson Structure",
           id: "",
+          updatedTime: new Date(),
         },
         {
           address: "200 W Sycamore Ave, Orange, CA 92866-1053",
@@ -70,12 +71,18 @@ describe("ChapmanApiBasedParkingRepositoryLoader", () => {
           },
           name: "Barrera",
           id: "",
+          updatedTime: new Date(),
         }
       ];
       expectedStructures[0].id = ChapmanApiBasedParkingRepositoryLoader.generateId(expectedStructures[0].address);
       expectedStructures[1].id = ChapmanApiBasedParkingRepositoryLoader.generateId(expectedStructures[1].address);
 
       const structuresFromLoader = await loader.repository.getParkingStructures();
+
+      // Set updatedTimeMs on expected data to avoid comparison
+      expectedStructures[0].updatedTime = structuresFromLoader[0].updatedTime;
+      expectedStructures[1].updatedTime = structuresFromLoader[1].updatedTime;
+
       expect(structuresFromLoader).toEqual(expectedStructures);
     });
 
diff --git a/test/notifications/schedulers/ETANotificationSchedulerTests.test.ts b/test/notifications/schedulers/ETANotificationSchedulerTests.test.ts
index db6a94b..1c5b819 100644
--- a/test/notifications/schedulers/ETANotificationSchedulerTests.test.ts
+++ b/test/notifications/schedulers/ETANotificationSchedulerTests.test.ts
@@ -52,6 +52,7 @@ describe("ETANotificationScheduler", () => {
       stopId: stop.id,
       secondsRemaining: 120,
       systemId: "1",
+      updatedTime: new Date(),
     };
 
     const notificationData1 = {
diff --git a/test/repositories/InMemoryParkingRepositoryTests.test.ts b/test/repositories/InMemoryParkingRepositoryTests.test.ts
index b656c81..d358d14 100644
--- a/test/repositories/InMemoryParkingRepositoryTests.test.ts
+++ b/test/repositories/InMemoryParkingRepositoryTests.test.ts
@@ -13,7 +13,8 @@ describe("InMemoryParkingRepository", () => {
     id: "1",
     name: "Anderson Parking Structure",
     capacity: 100,
-    address: "300 E Walnut Ave, Orange, CA 92867"
+    address: "300 E Walnut Ave, Orange, CA 92867",
+    updatedTime: new Date(),
   };
 
   beforeEach(() => {
diff --git a/test/resolvers/ParkingSystemResolverTests.test.ts b/test/resolvers/ParkingSystemResolverTests.test.ts
index 9515c18..951e2c2 100644
--- a/test/resolvers/ParkingSystemResolverTests.test.ts
+++ b/test/resolvers/ParkingSystemResolverTests.test.ts
@@ -4,6 +4,7 @@ import { setupTestServerContext, setupTestServerHolder } from "../testHelpers/ap
 import { InterchangeSystem } from "../../src/entities/InterchangeSystem";
 import assert = require("node:assert");
 
+
 describe("ParkingSystemResolver", () => {
   const holder = setupTestServerHolder();
   const context = setupTestServerContext();
@@ -40,6 +41,7 @@ describe("ParkingSystemResolver", () => {
               longitude
             }
             address
+            updatedTime
           }
         }
       }
@@ -47,15 +49,24 @@ describe("ParkingSystemResolver", () => {
     `
 
     it("gets parking structures associated with the system id", async () => {
-      const expectedParkingStructures = generateParkingStructures();
+      let expectedParkingStructures = generateParkingStructures();
       await Promise.all(expectedParkingStructures.map(async (structure) => {
         await context.systems[0].parkingRepository?.addOrUpdateParkingStructure(structure);
       }));
 
+      // Dates are transformed into epoch timestamps when serialized
+      expectedParkingStructures = expectedParkingStructures.map((structure) => {
+        const newStructure = { ...structure };
+        // @ts-ignore
+        newStructure.updatedTime = newStructure.updatedTime.getTime();
+        return newStructure;
+      });
+
       const response = await getResponseFromQueryNeedingSystemId(query);
 
       assert(response.body.kind === "single");
       expect(response.body.singleResult.errors).toBeUndefined();
+
       const parkingStructures = (response.body.singleResult.data as any).system.parkingSystem.parkingStructures;
       expect(parkingStructures).toEqual(expectedParkingStructures);
     });
@@ -65,7 +76,9 @@ describe("ParkingSystemResolver", () => {
 
       assert(response.body.kind === "single");
       expect(response.body.singleResult.errors).toBeUndefined();
+
       const parkingStructures = (response.body.singleResult.data as any).system.parkingSystem.parkingStructures;
+
       expect(parkingStructures).toHaveLength(0);
     });
   });
@@ -87,6 +100,7 @@ describe("ParkingSystemResolver", () => {
                 longitude
               }
               address
+              updatedTime
             }
           }
         }
@@ -111,11 +125,14 @@ describe("ParkingSystemResolver", () => {
         await context.systems[0].parkingRepository?.addOrUpdateParkingStructure(structure);
       }));
       const expectedParkingStructure = generatedParkingStructures[1];
+      // @ts-ignore
+      expectedParkingStructure.updatedTime = expectedParkingStructure.updatedTime.getTime();
 
       const response = await getResponseForParkingStructureQuery(expectedParkingStructure.id);
 
       assert(response.body.kind === "single");
       expect(response.body.singleResult.errors).toBeUndefined();
+
       const parkingStructure = (response.body.singleResult.data as any).system.parkingSystem.parkingStructure;
       expect(parkingStructure).toEqual(expectedParkingStructure);
     });
@@ -132,6 +149,7 @@ describe("ParkingSystemResolver", () => {
 
       assert(response.body.kind === "single");
       expect(response.body.singleResult.errors).toBeUndefined();
+
       const parkingStructure = (response.body.singleResult.data as any).system.parkingSystem.parkingStructure;
       expect(parkingStructure).toBeNull();
     });
diff --git a/test/testHelpers/mockDataGenerators.ts b/test/testHelpers/mockDataGenerators.ts
index b28cff7..dea9037 100644
--- a/test/testHelpers/mockDataGenerators.ts
+++ b/test/testHelpers/mockDataGenerators.ts
@@ -16,7 +16,8 @@ export function generateParkingStructures(): IParkingStructure[] {
       "id": "b0723baf8a6b8bcc37c821473373049e",
       "name": "Anderson Structure",
       "spotsAvailable": 163,
-      "address": "300 E Walnut, Orange, CA 92867"
+      "address": "300 E Walnut, Orange, CA 92867",
+      updatedTime: new Date(),
     },
     {
       "capacity": 692,
@@ -27,7 +28,8 @@ export function generateParkingStructures(): IParkingStructure[] {
       "id": "81b9e1ed004cf6def2e6c568aaf79ece",
       "name": "Barrera",
       "spotsAvailable": 179,
-      "address": "200 W Sycamore Ave, Orange, CA 92866-1053"
+      "address": "200 W Sycamore Ave, Orange, CA 92866-1053",
+      updatedTime: new Date(),
     }
   ];
 }
@@ -43,7 +45,8 @@ export function generateMockShuttles(): IShuttle[] {
         latitude: 10,
         longitude: 20
       },
-      orientationInDegrees: 25.163
+      orientationInDegrees: 25.163,
+      updatedTime: new Date(),
     },
     {
       id: "sh2",
@@ -54,7 +57,8 @@ export function generateMockShuttles(): IShuttle[] {
         latitude: 15,
         longitude: 25
       },
-      orientationInDegrees: 50.912
+      orientationInDegrees: 50.912,
+      updatedTime: new Date(),
     },
     {
       id: "sh3",
@@ -65,40 +69,41 @@ export function generateMockShuttles(): IShuttle[] {
         latitude: 30,
         longitude: 40
       },
-      orientationInDegrees: 321.019
+      orientationInDegrees: 321.019,
+      updatedTime: new Date(),
     },
   ];
 }
 
 export function generateMockRoutes(): IRoute[] {
   return [
-    { id: "r1", name: "Route 1", color: "red", systemId: "sys1", polylineCoordinates: [] },
-    { id: "r2", name: "Route 2", color: "blue", systemId: "sys2", polylineCoordinates: [] },
-    { id: "r3", name: "Route 3", color: "green", systemId: "sys3", polylineCoordinates: [] },
+    { id: "r1", name: "Route 1", color: "red", systemId: "sys1", polylineCoordinates: [], updatedTime: new Date() },
+    { id: "r2", name: "Route 2", color: "blue", systemId: "sys2", polylineCoordinates: [], updatedTime: new Date() },
+    { id: "r3", name: "Route 3", color: "green", systemId: "sys3", polylineCoordinates: [], updatedTime: new Date() },
   ];
 }
 
 export function generateMockStops(): IStop[] {
   return [
-    { id: "st1", name: "Stop A", systemId: "sys1", coordinates: { latitude: 10, longitude: 20 } },
-    { id: "st2", name: "Stop B", systemId: "sys2", coordinates: { latitude: 15, longitude: 25 } },
-    { id: "st3", name: "Stop C", systemId: "sys3", coordinates: { latitude: 30, longitude: 40 } },
+    { id: "st1", name: "Stop A", systemId: "sys1", coordinates: { latitude: 10, longitude: 20 }, updatedTime: new Date() },
+    { id: "st2", name: "Stop B", systemId: "sys2", coordinates: { latitude: 15, longitude: 25 }, updatedTime: new Date() },
+    { id: "st3", name: "Stop C", systemId: "sys3", coordinates: { latitude: 30, longitude: 40 }, updatedTime: new Date() },
   ];
 }
 
 export function generateMockOrderedStops(): IOrderedStop[] {
   return [
-    { stopId: "st1", routeId: "r1", position: 1, systemId: "sys1" },
-    { stopId: "st1", routeId: "r2", position: 2, systemId: "sys1" },
-    { stopId: "st2", routeId: "r1", position: 3, systemId: "sys1" },
-    { stopId: "st2", routeId: "r2", position: 4, systemId: "sys1" },
+    { stopId: "st1", routeId: "r1", position: 1, systemId: "sys1", updatedTime: new Date(), },
+    { stopId: "st1", routeId: "r2", position: 2, systemId: "sys1", updatedTime: new Date(), },
+    { stopId: "st2", routeId: "r1", position: 3, systemId: "sys1", updatedTime: new Date(), },
+    { stopId: "st2", routeId: "r2", position: 4, systemId: "sys1", updatedTime: new Date(), },
   ];
 }
 
 export function generateMockEtas(): IEta[] {
   return [
-    { shuttleId: "sh1", stopId: "st1", secondsRemaining: 120, systemId: "sys1" },
-    { shuttleId: "sh1", stopId: "st2", secondsRemaining: 180, systemId: "sys1" },
-    { shuttleId: "sh2", stopId: "st3", secondsRemaining: 240, systemId: "sys1" },
+    { shuttleId: "sh1", stopId: "st1", secondsRemaining: 120, systemId: "sys1", updatedTime: new Date() },
+    { shuttleId: "sh1", stopId: "st2", secondsRemaining: 180, systemId: "sys1", updatedTime: new Date() },
+    { shuttleId: "sh2", stopId: "st3", secondsRemaining: 240, systemId: "sys1", updatedTime: new Date() },
   ];
 }