diff --git a/docs/design/sim.md b/docs/design/sim.md
index 75e7747db1..e5fd6d8100 100644
--- a/docs/design/sim.md
+++ b/docs/design/sim.md
@@ -167,6 +167,14 @@ Next thoughts:
 	- try to be close to building, random jitter to be a little far away
 	- if this process is somewhat stable, then should be fine. doesnt need to be perfectly stable -- removing lanes somewhere might put more pressure on another lane.
 
+
+steps for this change:
+= give cars an optional building as an owner, make a query for parking sim to find available cars, hook up UI debug
+	= initially randomly assign a building in the neighborhood
+- start seeding parked cars per building instead of per spot
+	- make sure stability is vaguely preserved
+- make peds that'll use a car pick from a house with an available car
+
 ## Traces between worlds
 
 Alright, now how do we even compare trip progress to show it visually? This is
diff --git a/editor/src/objects.rs b/editor/src/objects.rs
index 2ced1294f5..d0a5648379 100644
--- a/editor/src/objects.rs
+++ b/editor/src/objects.rs
@@ -43,6 +43,13 @@ impl ID {
             ID::Turn(_) => {}
             ID::Building(id) => {
                 map.get_b(id).dump_debug();
+                let parked_cars = sim.get_parked_cars_by_owner(id);
+                println!(
+                    "{} parked cars are owned by {}: {:?}",
+                    parked_cars.len(),
+                    id,
+                    parked_cars.iter().map(|p| p.car).collect::<Vec<CarID>>()
+                );
             }
             ID::Car(id) => {
                 sim.debug_car(id);
diff --git a/sim/src/driving.rs b/sim/src/driving.rs
index d3813abdc2..ca8ea2e24e 100644
--- a/sim/src/driving.rs
+++ b/sim/src/driving.rs
@@ -5,7 +5,7 @@ use geom::EPSILON_DIST;
 use intersections::{IntersectionSimState, Request};
 use kinematics;
 use kinematics::Vehicle;
-use map_model::{LaneID, Map, Trace, Traversable, TurnID, LANE_THICKNESS};
+use map_model::{BuildingID, LaneID, Map, Trace, Traversable, TurnID, LANE_THICKNESS};
 use multimap::MultiMap;
 use ordered_float::NotNaN;
 use parking::ParkingSimState;
@@ -38,6 +38,7 @@ struct Car {
     id: CarID,
     // None for buses
     trip: Option<TripID>,
+    owner: Option<BuildingID>,
     on: Traversable,
     speed: Speed,
     dist_along: Distance,
@@ -492,7 +493,7 @@ impl DrivingSimState {
     pub fn tooltip_lines(&self, id: CarID) -> Option<Vec<String>> {
         if let Some(c) = self.cars.get(&id) {
             Some(vec![
-                format!("Car {:?}, part of {:?}", id, c.trip),
+                format!("Car {:?}, part of {:?}, owned by {:?}", id, c.trip, c.owner),
                 format!(
                     "On {:?}, speed {:?}, dist along {:?}",
                     c.on, c.speed, c.dist_along
@@ -591,7 +592,7 @@ impl DrivingSimState {
                     c.parking = Some(ParkingState {
                         is_parking: true,
                         started_at: time,
-                        tuple: ParkedCar::new(*id, *spot, c.vehicle.clone()),
+                        tuple: ParkedCar::new(*id, *spot, c.vehicle.clone(), c.owner),
                     });
                 }
                 Action::WorkOnParking => {
@@ -677,29 +678,23 @@ impl DrivingSimState {
         &mut self,
         events: &mut Vec<Event>,
         time: Tick,
-        car: CarID,
-        trip: Option<TripID>,
-        maybe_parked_car: Option<ParkedCar>,
-        vehicle: Vehicle,
-        dist_along: Distance,
-        start: LaneID,
-        router: Router,
         map: &Map,
+        params: CreateCar,
     ) -> bool {
         // If not, we have a parking lane much longer than a driving lane...
-        assert!(dist_along <= map.get_l(start).length());
+        assert!(params.dist_along <= map.get_l(params.start).length());
 
         // Is it safe to enter the lane right now? Start scanning ahead of where we'll enter, so we
         // don't hit somebody's back
-        if let Some(other) =
-            self.lanes[start.0].first_car_behind(dist_along + Vehicle::worst_case_following_dist())
+        if let Some(other) = self.lanes[params.start.0]
+            .first_car_behind(params.dist_along + Vehicle::worst_case_following_dist())
         {
             let other_dist = self.cars[&other].dist_along;
-            if other_dist >= dist_along {
+            if other_dist >= params.dist_along {
                 debug!(
                     "{} can't spawn, because they'd wind up too close ({}) behind {}",
-                    car,
-                    other_dist - dist_along,
+                    params.car,
+                    other_dist - params.dist_along,
                     other
                 );
                 return false;
@@ -709,13 +704,13 @@ impl DrivingSimState {
             let accel_for_other_to_stop = other_vehicle
                 .accel_to_follow(
                     self.cars[&other].speed,
-                    map.get_parent(start).get_speed_limit(),
-                    &vehicle,
-                    dist_along - other_dist,
+                    map.get_parent(params.start).get_speed_limit(),
+                    &params.vehicle,
+                    params.dist_along - other_dist,
                     0.0 * si::MPS,
                 ).unwrap();
             if accel_for_other_to_stop <= other_vehicle.max_deaccel {
-                debug!("{} can't spawn {} in front of {}, because {} would have to do {} to not hit {}", car, dist_along - other_dist, other, other, accel_for_other_to_stop, car);
+                debug!("{} can't spawn {} in front of {}, because {} would have to do {} to not hit {}", params.car, params.dist_along - other_dist, other, other, accel_for_other_to_stop, params.car);
                 return false;
             }
 
@@ -725,18 +720,19 @@ impl DrivingSimState {
         }
 
         self.cars.insert(
-            car,
+            params.car,
             Car {
-                id: car,
-                trip,
-                dist_along: dist_along,
+                id: params.car,
+                trip: params.trip,
+                owner: params.owner,
+                on: Traversable::Lane(params.start),
+                dist_along: params.dist_along,
                 speed: 0.0 * si::MPS,
-                on: Traversable::Lane(start),
-                vehicle,
+                vehicle: params.vehicle,
                 waiting_for: None,
                 debug: false,
-                is_bus: !maybe_parked_car.is_some(),
-                parking: maybe_parked_car.and_then(|parked_car| {
+                is_bus: !params.maybe_parked_car.is_some(),
+                parking: params.maybe_parked_car.and_then(|parked_car| {
                     Some(ParkingState {
                         is_parking: false,
                         started_at: time,
@@ -745,11 +741,11 @@ impl DrivingSimState {
                 }),
             },
         );
-        self.routers.insert(car, router);
-        self.lanes[start.0].insert_at(car, dist_along);
+        self.routers.insert(params.car, params.router);
+        self.lanes[params.start.0].insert_at(params.car, params.dist_along);
         events.push(Event::AgentEntersTraversable(
-            AgentID::Car(car),
-            Traversable::Lane(start),
+            AgentID::Car(params.car),
+            Traversable::Lane(params.start),
         ));
         true
     }
@@ -823,3 +819,14 @@ impl DrivingSimState {
         Some(r.trace_route(c.on, c.dist_along, map, dist_ahead))
     }
 }
+
+pub struct CreateCar {
+    pub car: CarID,
+    pub trip: Option<TripID>,
+    pub owner: Option<BuildingID>,
+    pub maybe_parked_car: Option<ParkedCar>,
+    pub vehicle: Vehicle,
+    pub start: LaneID,
+    pub dist_along: Distance,
+    pub router: Router,
+}
diff --git a/sim/src/helpers.rs b/sim/src/helpers.rs
index ce2cd3da1b..33d1c2f4d0 100644
--- a/sim/src/helpers.rs
+++ b/sim/src/helpers.rs
@@ -143,7 +143,11 @@ impl Sim {
 // Spawning helpers
 impl Sim {
     pub fn small_spawn(&mut self, map: &Map) {
-        self.seed_parked_cars(map.all_lanes().iter().map(|l| l.id).collect(), 0.5);
+        self.seed_parked_cars(
+            map.all_lanes().iter().map(|l| l.id).collect(),
+            &map.all_buildings().iter().map(|b| b.id).collect(),
+            0.5,
+        );
         self.seed_walking_trips(&map, 100);
         self.seed_driving_trips(&map, 100);
 
@@ -162,14 +166,28 @@ impl Sim {
         );*/    }
 
     pub fn big_spawn(&mut self, map: &Map) {
-        self.seed_parked_cars(map.all_lanes().iter().map(|l| l.id).collect(), 0.95);
+        self.seed_parked_cars(
+            map.all_lanes().iter().map(|l| l.id).collect(),
+            &map.all_buildings().iter().map(|b| b.id).collect(),
+            0.95,
+        );
         self.seed_walking_trips(&map, 1000);
         self.seed_driving_trips(&map, 1000);
     }
 
-    pub fn seed_parked_cars(&mut self, in_lanes: Vec<LaneID>, percent: f64) {
-        self.spawner
-            .seed_parked_cars(percent, in_lanes, &mut self.parking_state, &mut self.rng);
+    pub fn seed_parked_cars(
+        &mut self,
+        in_lanes: Vec<LaneID>,
+        owner_buildins: &Vec<BuildingID>,
+        percent: f64,
+    ) {
+        self.spawner.seed_parked_cars(
+            percent,
+            in_lanes,
+            owner_buildins,
+            &mut self.parking_state,
+            &mut self.rng,
+        );
     }
 
     pub fn seed_bus_route(&mut self, route: &BusRoute, map: &Map) -> Vec<CarID> {
@@ -186,9 +204,19 @@ impl Sim {
         )
     }
 
-    pub fn seed_specific_parked_cars(&mut self, lane: LaneID, spots: Vec<usize>) -> Vec<CarID> {
-        self.spawner
-            .seed_specific_parked_cars(lane, spots, &mut self.parking_state, &mut self.rng)
+    pub fn seed_specific_parked_cars(
+        &mut self,
+        lane: LaneID,
+        owner: BuildingID,
+        spots: Vec<usize>,
+    ) -> Vec<CarID> {
+        self.spawner.seed_specific_parked_cars(
+            lane,
+            owner,
+            spots,
+            &mut self.parking_state,
+            &mut self.rng,
+        )
     }
 
     pub fn seed_driving_trips(&mut self, map: &Map, num_cars: usize) {
diff --git a/sim/src/lib.rs b/sim/src/lib.rs
index 06813a15c9..c0048bf317 100644
--- a/sim/src/lib.rs
+++ b/sim/src/lib.rs
@@ -58,7 +58,7 @@ pub use events::Event;
 use geom::{Angle, Pt2D};
 pub use helpers::{load, SimFlags};
 pub use instrument::save_backtraces;
-use map_model::{LaneID, Trace, TurnID};
+use map_model::{BuildingID, LaneID, Trace, TurnID};
 use rand::{RngCore, SeedableRng, XorShiftRng};
 pub use scenario::{Neighborhood, Scenario, SeedParkedCars, SpawnOverTime};
 pub use sim::{Benchmark, Sim};
@@ -293,11 +293,22 @@ pub struct ParkedCar {
     pub car: CarID,
     pub spot: ParkingSpot,
     pub vehicle: kinematics::Vehicle,
+    pub owner: Option<BuildingID>,
 }
 
 impl ParkedCar {
-    pub fn new(car: CarID, spot: ParkingSpot, vehicle: kinematics::Vehicle) -> ParkedCar {
-        ParkedCar { car, spot, vehicle }
+    pub fn new(
+        car: CarID,
+        spot: ParkingSpot,
+        vehicle: kinematics::Vehicle,
+        owner: Option<BuildingID>,
+    ) -> ParkedCar {
+        ParkedCar {
+            car,
+            spot,
+            vehicle,
+            owner,
+        }
     }
 }
 
diff --git a/sim/src/parking.rs b/sim/src/parking.rs
index 0976f5feb8..ea388a1b8e 100644
--- a/sim/src/parking.rs
+++ b/sim/src/parking.rs
@@ -1,7 +1,7 @@
 use geom::{Angle, Polygon, Pt2D};
 use kinematics::Vehicle;
 use map_model;
-use map_model::{Lane, LaneID, LaneType, Map};
+use map_model::{BuildingID, Lane, LaneID, LaneType, Map};
 use std::iter;
 use {CarID, Distance, DrawCarInput, ParkedCar, ParkingSpot};
 
@@ -138,6 +138,25 @@ impl ParkingSimState {
     fn get_spot(&self, spot: ParkingSpot) -> &ParkingSpotGeometry {
         &self.lanes[spot.lane.0].spots[spot.idx]
     }
+
+    pub fn tooltip_lines(&self, id: CarID) -> Vec<String> {
+        let c = self.lookup_car(id).unwrap();
+        vec![format!("{} is parked, owned by {:?}", c.car, c.owner)]
+    }
+
+    pub fn get_parked_cars_by_owner(&self, id: BuildingID) -> Vec<&ParkedCar> {
+        let mut result: Vec<&ParkedCar> = Vec::new();
+        for l in &self.lanes {
+            for maybe_occupant in &l.occupants {
+                if let Some(o) = maybe_occupant {
+                    if o.owner == Some(id) {
+                        result.push(maybe_occupant.as_ref().unwrap());
+                    }
+                }
+            }
+        }
+        result
+    }
 }
 
 #[derive(Serialize, Deserialize)]
diff --git a/sim/src/scenario.rs b/sim/src/scenario.rs
index 53ec631522..53d63b30db 100644
--- a/sim/src/scenario.rs
+++ b/sim/src/scenario.rs
@@ -97,6 +97,7 @@ impl Scenario {
         for s in &self.seed_parked_cars {
             sim.seed_parked_cars(
                 neighborhoods[&s.neighborhood].find_matching_lanes(map),
+                &bldgs_per_neighborhood[&s.neighborhood],
                 s.percent_to_fill,
             );
         }
diff --git a/sim/src/sim.rs b/sim/src/sim.rs
index ad6f15bfa8..1c8e0b1a05 100644
--- a/sim/src/sim.rs
+++ b/sim/src/sim.rs
@@ -8,7 +8,7 @@ use driving::DrivingSimState;
 use geom::Pt2D;
 use instrument::capture_backtrace;
 use intersections::IntersectionSimState;
-use map_model::{IntersectionID, LaneID, LaneType, Map, Trace, Turn, TurnID};
+use map_model::{BuildingID, IntersectionID, LaneID, LaneType, Map, Trace, Turn, TurnID};
 use parking::ParkingSimState;
 use rand::{FromEntropy, SeedableRng, XorShiftRng};
 use spawn::Spawner;
@@ -21,8 +21,8 @@ use trips::TripManager;
 use view::WorldView;
 use walking::WalkingSimState;
 use {
-    AgentID, CarID, CarState, Distance, DrawCarInput, DrawPedestrianInput, Event, PedestrianID,
-    ScoreSummary, Tick, TripID, TIMESTEP,
+    AgentID, CarID, CarState, Distance, DrawCarInput, DrawPedestrianInput, Event, ParkedCar,
+    PedestrianID, ScoreSummary, Tick, TripID, TIMESTEP,
 };
 
 #[derive(Serialize, Deserialize, Derivative)]
@@ -280,7 +280,7 @@ impl Sim {
     pub fn car_tooltip(&self, car: CarID) -> Vec<String> {
         self.driving_state
             .tooltip_lines(car)
-            .unwrap_or(vec![format!("{} is parked", car)])
+            .unwrap_or(self.parking_state.tooltip_lines(car))
     }
 
     pub fn debug_car(&mut self, id: CarID) {
@@ -395,6 +395,10 @@ impl Sim {
             None => None,
         }
     }
+
+    pub fn get_parked_cars_by_owner(&self, id: BuildingID) -> Vec<&ParkedCar> {
+        self.parking_state.get_parked_cars_by_owner(id)
+    }
 }
 
 pub struct Benchmark {
diff --git a/sim/src/spawn.rs b/sim/src/spawn.rs
index 69bf9e7dd0..97964cc80d 100644
--- a/sim/src/spawn.rs
+++ b/sim/src/spawn.rs
@@ -1,5 +1,5 @@
 use abstutil::elapsed_seconds;
-use driving::DrivingSimState;
+use driving::{CreateCar, DrivingSimState};
 use kinematics::Vehicle;
 use map_model::{BuildingID, BusRoute, BusStopID, LaneID, Map, Pathfinder};
 use parking::ParkingSimState;
@@ -117,14 +117,17 @@ impl Spawner {
                         if driving_sim.start_car_on_lane(
                             events,
                             now,
-                            car,
-                            Some(trip),
-                            Some(parked_car.clone()),
-                            parked_car.vehicle.clone(),
-                            dist_along,
-                            start,
-                            Router::make_router_to_park(path, goal_bldg),
                             map,
+                            CreateCar {
+                                car,
+                                trip: Some(trip),
+                                owner: parked_car.owner,
+                                maybe_parked_car: Some(parked_car.clone()),
+                                vehicle: parked_car.vehicle.clone(),
+                                start,
+                                dist_along,
+                                router: Router::make_router_to_park(path, goal_bldg),
+                            },
                         ) {
                             trips.agent_starting_trip_leg(AgentID::Car(car), trip);
                             parking_sim.remove_parked_car(parked_car.clone());
@@ -178,14 +181,17 @@ impl Spawner {
             if driving_sim.start_car_on_lane(
                 events,
                 now,
-                id,
-                None,
-                None,
-                vehicle,
-                start_dist_along,
-                start,
-                Router::make_router_for_bus(path),
                 map,
+                CreateCar {
+                    car: id,
+                    trip: None,
+                    owner: None,
+                    maybe_parked_car: None,
+                    vehicle,
+                    start,
+                    dist_along: start_dist_along,
+                    router: Router::make_router_for_bus(path),
+                },
             ) {
                 transit_sim.bus_created(id, route_id, next_stop_idx);
                 info!("Spawned bus {} for route {} ({})", id, route.name, route_id);
@@ -205,6 +211,7 @@ impl Spawner {
         &mut self,
         percent_capacity_to_fill: f64,
         in_lanes: Vec<LaneID>,
+        owner_buildings: &Vec<BuildingID>,
         parking_sim: &mut ParkingSimState,
         base_rng: &mut XorShiftRng,
     ) {
@@ -228,6 +235,7 @@ impl Spawner {
                         car,
                         spot,
                         Vehicle::generate_typical_car(car, &mut rng),
+                        Some(*rng.choose(owner_buildings).unwrap()),
                     ));
                     self.car_id_counter += 1;
                 }
@@ -242,6 +250,7 @@ impl Spawner {
     pub fn seed_specific_parked_cars(
         &mut self,
         lane: LaneID,
+        owner: BuildingID,
         spot_indices: Vec<usize>,
         parking_sim: &mut ParkingSimState,
         rng: &mut XorShiftRng,
@@ -255,6 +264,7 @@ impl Spawner {
                     car,
                     spots[idx],
                     Vehicle::generate_typical_car(car, rng),
+                    Some(owner),
                 ));
                 self.car_id_counter += 1;
                 car