diff --git a/Cargo.lock b/Cargo.lock
index e4bf79c057..31ceb563e1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1248,6 +1248,7 @@ dependencies = [
  "downcast-rs",
  "enumset",
  "futures-channel",
+ "geo",
  "geojson",
  "geom",
  "getrandom",
diff --git a/game/Cargo.toml b/game/Cargo.toml
index 45eaa2a865..9ca85222bd 100644
--- a/game/Cargo.toml
+++ b/game/Cargo.toml
@@ -27,6 +27,7 @@ csv = "1.1.4"
 downcast-rs = "1.2.0"
 enumset = "1.0.3"
 futures-channel = { version = "0.3.12"}
+geo = "0.18"
 geojson = { version = "0.22.0", features = ["geo-types"] }
 geom = { path = "../geom" }
 getrandom = { version = "0.2.3", optional = true }
diff --git a/game/src/ltn/browse.rs b/game/src/ltn/browse.rs
index 7bdc952461..d565e19475 100644
--- a/game/src/ltn/browse.rs
+++ b/game/src/ltn/browse.rs
@@ -1,8 +1,10 @@
 use std::collections::HashSet;
 
+use anyhow::Result;
+
 use abstutil::Timer;
-use geom::Distance;
-use map_gui::tools::{CityPicker, DrawRoadLabels, Navigator, URLManager};
+use geom::{Distance, PolyLine, Pt2D};
+use map_gui::tools::{CityPicker, DrawRoadLabels, Navigator, PopupMsg, URLManager};
 use widgetry::mapspace::{ToggleZoomed, World, WorldOutcome};
 use widgetry::{
     lctrl, Color, EventCtx, GfxCtx, HorizontalAlignment, Key, Outcome, Panel, State, TextExt,
@@ -42,6 +44,10 @@ impl BrowseNeighborhoods {
                     .align_right(),
             ]),
             Toggle::checkbox(ctx, "highlight boundary roads", Key::H, true),
+            ctx.style()
+                .btn_outline
+                .text("Export to GeoJSON")
+                .build_def(ctx),
         ]))
         .aligned(HorizontalAlignment::Left, VerticalAlignment::Top)
         .build(ctx);
@@ -77,6 +83,18 @@ impl State<App> for BrowseNeighborhoods {
                 "search" => {
                     return Transition::Push(Navigator::new_state(ctx, app));
                 }
+                "Export to GeoJSON" => {
+                    return Transition::Push(match export_geojson(app) {
+                        Ok(path) => PopupMsg::new_state(
+                            ctx,
+                            "LTNs exported",
+                            vec![format!("Data exported to {}", path)],
+                        ),
+                        Err(err) => {
+                            PopupMsg::new_state(ctx, "Export failed", vec![err.to_string()])
+                        }
+                    });
+                }
                 _ => unreachable!(),
             }
         }
@@ -165,3 +183,100 @@ fn draw_boundary_roads(ctx: &EventCtx, app: &App) -> ToggleZoomed {
     }
     batch.build(ctx)
 }
+
+fn export_geojson(app: &App) -> Result<String> {
+    if cfg!(target_arch = "wasm32") {
+        bail!("Export only supported in the installed version");
+    }
+
+    use geo::algorithm::map_coords::MapCoordsInplace;
+    use geojson::{Feature, FeatureCollection, GeoJson, Geometry, Value};
+    use std::io::Write;
+
+    let map = &app.primary.map;
+    let mut features = Vec::new();
+
+    // All neighborhood boundaries
+    for (_, (block, color)) in &app.session.partitioning.neighborhoods {
+        let mut feature = Feature {
+            bbox: None,
+            geometry: Some(block.polygon.to_geojson(None)),
+            id: None,
+            properties: None,
+            foreign_members: None,
+        };
+        feature.set_property("type", "neighborhood");
+        feature.set_property("fill", color.as_hex());
+        features.push(feature);
+    }
+
+    // TODO Cells per neighborhood -- contouring the gridded version is hard!
+
+    // All modal filters
+    for (r, dist) in &app.session.modal_filters.roads {
+        let road = map.get_r(*r);
+        if let Ok((pt, angle)) = road.center_pts.dist_along(*dist) {
+            let road_width = road.get_width();
+            let pl = PolyLine::must_new(vec![
+                pt.project_away(0.8 * road_width, angle.rotate_degs(90.0)),
+                pt.project_away(0.8 * road_width, angle.rotate_degs(-90.0)),
+            ]);
+            let mut feature = Feature {
+                bbox: None,
+                geometry: Some(pl.to_geojson(None)),
+                id: None,
+                properties: None,
+                foreign_members: None,
+            };
+            feature.set_property("type", "road filter");
+            feature.set_property("stroke", "red");
+            features.push(feature);
+        }
+    }
+    for (_, filter) in &app.session.modal_filters.intersections {
+        let pl = filter.geometry(map).to_polyline();
+        let mut feature = Feature {
+            bbox: None,
+            geometry: Some(pl.to_geojson(None)),
+            id: None,
+            properties: None,
+            foreign_members: None,
+        };
+        feature.set_property("type", "diagonal filter");
+        feature.set_property("stroke", "red");
+        features.push(feature);
+    }
+
+    // Transform to WGS84
+    let gps_bounds = map.get_gps_bounds();
+    for feature in &mut features {
+        // geojson to geo
+        // This could be a Polygon, MultiPolygon, LineString
+        let mut geom: geo::Geometry<f64> = feature.geometry.take().unwrap().value.try_into()?;
+
+        geom.map_coords_inplace(|c| {
+            let gps = Pt2D::new(c.0, c.1).to_gps(gps_bounds);
+            (gps.x(), gps.y())
+        });
+
+        // geo to geojson
+        feature.geometry = Some(Geometry {
+            bbox: None,
+            value: Value::from(&geom),
+            foreign_members: None,
+        });
+    }
+
+    let gj = GeoJson::FeatureCollection(FeatureCollection {
+        features,
+        bbox: None,
+        foreign_members: None,
+    });
+
+    // Don't use abstio::write_json; it writes to local storage in web, where we want to eventually
+    // make the browser download something
+    let path = format!("ltn_{}.geojson", map.get_name().map);
+    let mut file = std::fs::File::create(&path)?;
+    write!(file, "{}", serde_json::to_string_pretty(&gj)?)?;
+    Ok(path)
+}
diff --git a/game/src/ltn/filters.rs b/game/src/ltn/filters.rs
index 0d8824609d..ca95bb1fb6 100644
--- a/game/src/ltn/filters.rs
+++ b/game/src/ltn/filters.rs
@@ -186,7 +186,7 @@ impl DiagonalFilter {
     }
 
     /// Physically where is the filter placed?
-    fn geometry(&self, map: &Map) -> Line {
+    pub fn geometry(&self, map: &Map) -> Line {
         let r1 = map.get_r(self.r1);
         let r2 = map.get_r(self.r2);