diff --git a/src/backend/data/schema.js b/src/backend/data/schema.js
index 7003c46f..6efc7ff1 100644
--- a/src/backend/data/schema.js
+++ b/src/backend/data/schema.js
@@ -456,6 +456,14 @@ const GraphQLListContainer = new GraphQLObjectType({
   interfaces: [nodeInterface]
 })
 
+const GeoPoint = new GraphQLInputObjectType({
+  name: 'GeoPoint',
+  fields: {
+    lat: {type: GraphQLFloat},
+    lon: {type: GraphQLFloat},
+  }
+})
+
 const GraphQLUser = new GraphQLObjectType({
   name: 'User',
   description: 'User of ground control',
@@ -554,10 +562,13 @@ const GraphQLUser = new GraphQLObjectType({
     intervieweeForCallAssignment: {
       type: GraphQLPerson,
       args: {
-        callAssignmentId: {type: GraphQLString}
+        callAssignmentId: {type: GraphQLString},
+        center: {type: GeoPoint},
+        radiusMeters: {type: GraphQLFloat}
       },
-      resolve: async(user, {callAssignmentId}, {rootValue}) => {
-
+      resolve: async(
+        user, {callAssignmentId, center, radiusMeters}, {rootValue}
+      ) => {
         let localCallAssignmentId = fromGlobalId(callAssignmentId)
         if (localCallAssignmentId.type !== 'CallAssignment')
           localCallAssignmentId = callAssignmentId
@@ -647,6 +658,21 @@ const GraphQLUser = new GraphQLObjectType({
         if (userAddress)
           query = query.whereNot('bsd_people.cons_id', userAddress.cons_id)
 
+        // Filter by distance from a geographical point.
+        // Spatial ref 4326 is WGS 84, in degrees
+        // Spatial ref 900913 is Google Web Mercator, in meters
+        if (center && radiusMeters > 0) {
+          query = query.whereRaw(`
+            ST_DWithin(bsd_addresses.geom,
+              ST_Transform(
+                ST_SetSRID(ST_MakePoint(${center.lon}, ${center.lat}), 4326),
+                900913
+              ),
+              ${radiusMeters}
+            )
+          `)
+        }
+
         log.info(`Running query: ${query}`)
 
         let person    = await query
diff --git a/src/frontend/app.js b/src/frontend/app.js
index 563d4735..c1e42c95 100644
--- a/src/frontend/app.js
+++ b/src/frontend/app.js
@@ -204,6 +204,7 @@ ReactDOM.render(
             ...CallAssignmentQueries,
             ...CurrentUserQueries
           }}
+          queryParams={['ll', 'miles']}
           renderLoading={() => <Loading />}
         />
       </Route>
diff --git a/src/frontend/components/CallAssignment.js b/src/frontend/components/CallAssignment.js
index 3ebc24a9..3369a6dc 100644
--- a/src/frontend/components/CallAssignment.js
+++ b/src/frontend/components/CallAssignment.js
@@ -12,6 +12,7 @@ import SubmitCallSurvey from '../mutations/SubmitCallSurvey'
 import CallStatsBar from './CallStatsBar'
 import MutationHandler from './MutationHandler'
 import {PhoneNumberFormat, PhoneNumberUtil} from 'google-libphonenumber'
+import getDefaultQuery from '../helpers/getDefaultQuery'
 const phoneUtil = PhoneNumberUtil.getInstance()
 
 const SurveyRenderers = {
@@ -408,8 +409,29 @@ ${userFirstName}`
   }
 }
 
+// Convert the query parameters 'll' and 'miles' into the API arguments
+// for the center and radius of the filter region.
+var center = null;
+var radiusMeters = null;
+
+var queryParams = getDefaultQuery({
+  ll: null,  // URL query parameter: point in lat,lon format
+  miles: null  // URL query parameter: radius in miles
+})
+var llParts = (queryParams.ll || '').split(',')
+if (llParts.length === 2) {
+  center = {lat: Number(llParts[0]), lon: Number(llParts[1])}
+}
+if (queryParams.miles) {
+  radiusMeters = Number(queryParams.miles) * 1609.34
+}
+
 export default Relay.createContainer(CallAssignment, {
-  initialVariables: { id: '' },
+  initialVariables: {
+    id: '',
+    center: center,
+    radiusMeters: radiusMeters
+  },
   fragments: {
     callAssignment: () => Relay.QL`
       fragment on CallAssignment {
@@ -428,9 +450,13 @@ export default Relay.createContainer(CallAssignment, {
       fragment on User {
         id
         firstName
-        allCallsMade:callsMade(forAssignmentId:$id)
-        completedCallsMade:callsMade(forAssignmentId:$id,completed:true)
-        intervieweeForCallAssignment(callAssignmentId:$id) {
+        allCallsMade: callsMade(forAssignmentId: $id)
+        completedCallsMade: callsMade(forAssignmentId: $id, completed: true)
+        intervieweeForCallAssignment(
+          callAssignmentId: $id,
+          center: $center,
+          radiusMeters: $radiusMeters
+        ) {
           id
           prefix
           firstName
diff --git a/src/frontend/helpers/convertType.js b/src/frontend/helpers/convertType.js
new file mode 100644
index 00000000..2b389e92
--- /dev/null
+++ b/src/frontend/helpers/convertType.js
@@ -0,0 +1,26 @@
+const convertType = (value) => {
+  if (typeof value === 'object'){
+    let updatedValue = {}
+    Object.keys(value).forEach((key) => {
+      const currentValue = convertType(value[key])
+      if (currentValue != undefined)
+        value[key] = currentValue
+    })
+    return value
+  }
+  else if (value === 'none')
+    return null
+  else if (value === 'true')
+    return true
+  else if (value === 'false')
+    return false
+  else if (value != '' && !isNaN(value) && String(Number(value)) === value)
+    return Number(value)
+  else if (value)
+    return String(value)
+  else {
+    return undefined
+  }
+}
+
+export default convertType
diff --git a/src/frontend/helpers/getDefaultQuery.js b/src/frontend/helpers/getDefaultQuery.js
new file mode 100644
index 00000000..aa69548f
--- /dev/null
+++ b/src/frontend/helpers/getDefaultQuery.js
@@ -0,0 +1,18 @@
+import qs from 'qs'
+import convertType from './convertType'
+
+export default function(defaultParams) {
+  const hashParams = convertType(qs.parse(location.hash.substr(1), { strictNullHandling: true }))
+  if (hashParams.query){
+    try {
+      let newQueryParams = {...defaultParams, ...hashParams.query}
+      newQueryParams.filters = {...defaultParams.filters, ...hashParams.query.filters}
+      return newQueryParams
+    }
+    catch(ex) {
+      console.error('Invalid query parameters', ex)
+    }
+  }
+
+  return {...defaultParams, ...hashParams}
+}