Methodology & sources

Source and vintage

Every route on OHV Trail Finder is a real feature read from the U.S. Forest Service's Enterprise Data Warehouse (EDW) Motor Vehicle Use Map map service — the Roads layer and the Trails layer — over plain public HTTP, no key required. Nothing here is scraped, modelled, or bought from a vendor.

The data has no per-feature edit date, so the vintage stamp is the pull date: USFS EDW MVUM, retrieved 2026-07-11. It is shown on every district and forest page. A new pull moves the stamp. In all, this covers 448 ranger districts across 40 states and 106 national forests — 231,615.7 miles of motorized routes.

How the miles, routes and vehicle access are derived

Both layers carry the same rich attribute schema, already tagged with a forest name and district name — so grouping routes into ranger districts needs no spatial join. For each district we sum the mapped length of its road and trail segments into total motorized miles (and the roads/trails split), count the segments as the route count, and read the per-vehicle-class open flags to build the access matrix.

For each of 17 vehicle classes — highway-legal classes, off-highway machines over and under 50 inches, core OHV (ATV, motorcycle, other wheeled), and e-bikes by class — the MVUM records an open flag and a season window per route. We report, per class, the open miles, the route count, and the season. A class with no open route in a district is shown as “Not designated,” never coerced to zero and never guessed.

Seasons

Each route carries a season token — yearlong or seasonal — and, when seasonal, a dated MM/DD–MM/DD window. We roll these up per district into year-round vs seasonal miles and an open/close envelope, and show each vehicle class's own season in the access matrix. Where a class mixes yearlong and seasonal routes, its season reads “Varies by route.” A route's window is never invented; if the source has none, none is shown.

Assigning each district to a state

The MVUM data has no state field, and national forests routinely span state lines (the Black Hills straddle Wyoming and South Dakota, for example). We assign each district to a state by a point-in-polygon test of a robust district location against U.S. Census TIGERweb state boundaries — resolving multi-state forests correctly at the district grain. A multi-state forest therefore appears under each state it touches, listing only that state's districts.

Null-geometry districts are excluded, not faked

A small number of districts appear in the MVUM attributes but return no usable route geometry from the service (the Tonto National Forest is the notable example). Because we cannot draw a map, measure miles, or build a GPX for them honestly, those districts are excluded from the site entirely rather than published as thin or zero-mile pages. Every district you can open here has real, measured route data behind it.

The route maps and basemap tiles

Each district page shows its routes two ways: an inline static map that makes no network request and works with JavaScript off, and — only when you choose to open it — an interactive map that draws the same routes over a U.S. Geological Survey The National Map basemap (topographic by default, satellite on a toggle). Those public-domain government basemap tiles, served by the USGS, are the site's one external dependency, and they load only after you open a map. The map library itself is served from this site — not a third-party CDN — and no analytics or tracking is attached to the tiles.

The grain is the ranger district — never the route

Pages exist for districts, forests, states and vehicle×state views — never one page per route segment. The full route data lives inside each district page (a collapsible route table) and in the GPX download. A page per segment would mean hundreds of thousands of near-identical thin pages; district-level aggregation of genuinely distinct route data is the honest, useful grain.

These pages are informational, not legal documents

This is the most important note on the site. Every mile, designation and season here is an informational summary of the MVUM data. It is not the official Motor Vehicle Use Map, and the federal metadata itself states this data is not a legal document. Designations, closures and conditions change. The controlling document is each district's official MVUM, which every district and forest page links, and which you must carry and follow when you ride.

Official-link policy

We do not fabricate per-district MVUM PDF URLs. Each page links the forest's official Forest Service page — the verifiable entry point to that forest's Motor Vehicle Use Map — and labels it as the official source. If a more specific verified link is not resolvable, the forest-level link is used rather than a guessed URL.

Update cadence

The MVUM service is refreshed by the Forest Service over time. This site re-pulls on a periodic cadence; because the data has no per-feature date, a re-pull simply moves the vintage stamp shown on every page. Between pulls the published figures are immutable.