We maintain locations on over a quarter million roadway miles and 13,000 waterway miles in all 50 states and growing.
Our objective is to maintain complete and current sets of locations on every highway with physical mile marker signs to the nearest 0.01 miles. Most other data if it exists, including those from authoritative sources, are incomplete, unorganized, do not match the physical locations, and/or out-of-date. Some state records are based upon a linear reference system and do not match the actual sign locations. Some states do not allow any commercial use of their data.
Our data follows the alignment of each roadway for best accuracy in real-time tracking and location applications. The points are typically located on the centerlines. Our products are best for those who wish to have a single source for nationwide coverage that is consistent, up-to-date, easily consumable, and used in any type of commercial application.
Mile markers function like an address along a highway. Even with modern GPS, we typically don't send someone a latitude/longitude of our home to get directions. We use an address instead for ease of communication that works with or without technology. Likewise, mile markers are commonly used by first responders and roadside assistance to locate you faster on highway, keep track of traffic violations and incidents, reporting a hazard on a road, and aiding in navigation.
On occasion, yes. There are a number of reasons for this. If a highway gets reclassified from a U.S. or state highway to an Interstate, for example, it commonly requires new mile markers to match the corridor. In other cases, roadways that get rehabilitated or reconstructed commonly have new signage. The new signage may be placed at new locations, particularly in cases where the old signage was not located accurately.