diff --git a/convert_osm/tests/determinism.rs b/convert_osm/tests/determinism.rs
index 643d86242f..286ba9b480 100644
--- a/convert_osm/tests/determinism.rs
+++ b/convert_osm/tests/determinism.rs
@@ -8,6 +8,7 @@ fn convert_twice() {
         elevation: "../data/input/N47W122.hgt".to_string(),
         traffic_signals: "../data/input/TrafficSignals.shp".to_string(),
         parcels: "../data/seattle_parcels.abst".to_string(),
+		parking_shapes: "../data/shapes/blockface".to_string(),
         gtfs: "../data/input/google_transit_2018_18_08".to_string(),
         neighborhoods: "../data/input/neighborhoods.geojson".to_string(),
         output: "".to_string(),
diff --git a/docs/design/time_travel.md b/docs/design/time_travel.md
index 6d609a08e5..7ed06c89da 100644
--- a/docs/design/time_travel.md
+++ b/docs/design/time_travel.md
@@ -18,6 +18,8 @@ if each plugin should sort of declare a dependency on a live sim or if at a
 higher level, the list of plugins should change?
 
 Some initial steps:
-- make a plugin that asks for all Draw stuff every tick and just saves it
+= make a plugin that asks for all Draw stuff every tick and just saves it
 - activate the time travel plugin and have keys to go back/forward
+- supply the Draw{Car,Ped} stuff from the time travel plugin, not the sim
 - deactivate lots of other plugins while in this mode
+	- make sim ctrl a proper plugin
diff --git a/editor/src/plugins/mod.rs b/editor/src/plugins/mod.rs
index 66065ed9f9..6f89f74218 100644
--- a/editor/src/plugins/mod.rs
+++ b/editor/src/plugins/mod.rs
@@ -23,6 +23,7 @@ pub mod show_route;
 pub mod sim_controls;
 pub mod steep;
 pub mod stop_sign_editor;
+pub mod time_travel;
 pub mod traffic_signal_editor;
 pub mod turn_cycler;
 pub mod warp;
diff --git a/editor/src/plugins/time_travel.rs b/editor/src/plugins/time_travel.rs
new file mode 100644
index 0000000000..f8c9535a87
--- /dev/null
+++ b/editor/src/plugins/time_travel.rs
@@ -0,0 +1,54 @@
+use plugins::{Plugin, PluginCtx};
+use map_model::Map;
+use std::collections::BTreeMap;
+use sim::{CarID, DrawCarInput, PedestrianID, DrawPedestrianInput, Sim, AgentID};
+
+pub struct TimeTravel {
+    state_per_tick: Vec<StateAtTime>,
+}
+
+struct StateAtTime {
+    cars: BTreeMap<CarID, DrawCarInput>,
+    peds: BTreeMap<PedestrianID, DrawPedestrianInput>,
+}
+
+impl TimeTravel {
+    pub fn new() -> TimeTravel {
+        TimeTravel {
+            state_per_tick: Vec::new(),
+        }
+    }
+
+    fn record_state(&mut self, sim: &Sim, map: &Map) {
+        // Record state for this tick, if needed.
+        let tick = sim.time.to_inner() as usize;
+        if tick + 1 == self.state_per_tick.len() {
+            return;
+        }
+        assert_eq!(tick, self.state_per_tick.len());
+
+        let mut state = StateAtTime {
+            cars: BTreeMap::new(),
+            peds: BTreeMap::new(),
+        };
+        for agent in sim.active_agents().into_iter() {
+            match agent {
+                AgentID::Car(id) => {
+                    state.cars.insert(id, sim.get_draw_car(id, map).unwrap());
+                }
+                AgentID::Pedestrian(id) => {
+                    state.peds.insert(id, sim.get_draw_ped(id, map).unwrap());
+                }
+            };
+        }
+        self.state_per_tick.push(state);
+    }
+}
+
+impl Plugin for TimeTravel {
+    fn event(&mut self, ctx: PluginCtx) -> bool {
+        self.record_state(&ctx.primary.sim, &ctx.primary.map);
+
+        false
+    }
+}
diff --git a/editor/src/ui.rs b/editor/src/ui.rs
index 797a7328c5..a208ab05a9 100644
--- a/editor/src/ui.rs
+++ b/editor/src/ui.rs
@@ -257,6 +257,7 @@ impl PerMapUI {
                 Box::new(plugins::map_edits::EditsManager::new()),
                 Box::new(plugins::chokepoints::ChokepointsFinder::new()),
                 Box::new(neighborhood_summary),
+                Box::new(plugins::time_travel::TimeTravel::new()),
             ],
         };
         (state, plugins)
diff --git a/sim/src/physics.rs b/sim/src/physics.rs
index a7aa95faf2..e1c20bd052 100644
--- a/sim/src/physics.rs
+++ b/sim/src/physics.rs
@@ -18,6 +18,10 @@ pub type Acceleration = si::MeterPerSecond2<f64>;
 pub struct Tick(u32);
 
 impl Tick {
+    pub fn to_inner(&self) -> u32 {
+        self.0
+    }
+
     pub fn zero() -> Tick {
         Tick(0)
     }