Red marks a highway stretch where none of AT&T, T-Mobile or Verizon reports 4G LTE coverage (5/1 Mbps) for a moving vehicle in its FCC filing. It does not mean your phone will have no signal. Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming.
Carrier-reported and approximate. Coverage is checked only at each mile marker. 5G-only coverage, regional carriers and roaming partners are not counted. What this means
Source: FCC National Broadband Map, mobile broadband availability as of December 31, 2025, 4G LTE, in-vehicle. Processed by MileCheck October 26, 2026.
MileCheck keeps mile marker data for all 50 states on the phone, so your nearest mile marker still shows with no signal. That is the first thing dispatch asks for.
App Store Google PlayWhat this means. These are the coverage maps each carrier files with the FCC, not measured signal. Carriers miss real signal in places and claim signal that is not there in others, and mountain passes are where the maps are weakest. Red means none of the three carriers reports coverage, not that your phone will have none. You may still reach 911 through another carrier's network, a regional carrier or satellite messaging.
How this was built. For every mile marker in the MileCheck milepost data in these states, we looked up the H3 hexagon (about 0.1 square kilometer) that contains it in each carrier's FCC filing, and kept only the "in a moving vehicle" layer at 4G LTE 5/1 Mbps. The lines between mile markers are drawn in the color of the marker they start at. They are not a survey of the whole road, and a short gap between two markers can hide a stretch with no reported coverage. 5G-only coverage is not counted. Regional carriers are not shown, and neither are the partner networks a carrier roams on, so a Verizon phone can have service where Verizon's own filing shows none (much of eastern Utah and Wyoming works this way).
States mapped so far: Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming. More states are coming. If you know a stretch where the map is wrong, tell us at feedback@milecheckapp.com. You can also challenge a carrier's map with the FCC on the National Broadband Map. The FCC takes mobile challenges backed by speed tests.
Related: How to contact help with no cell signal · Mile marker map · Mountain pass conditions · Road conditions map
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