What do blue background signs indicate on US roadways?

Blue background signs on U.S. roadways indicate motorist services.

These signs help drivers find practical facilities and assistance along a route, including fuel, food, lodging, hospitals, telephones, rest areas, and other traveler amenities. Their purpose is service information rather than route identification, traffic regulation, or hazard warning.

The color system helps motorists scan signs quickly. Green is normally used for destinations, directions, exits, and distances. Brown identifies recreational, cultural, scenic, and historic attractions. Blue therefore signals that a driver is approaching a service or facility useful during a trip.

Route markers can appear on signs with other colors, but the familiar Interstate shield is a separate red-white-blue symbol, not a blue service sign. Large blue logo panels at freeway exits are another related example: they advertise nearby businesses such as restaurants, fuel stations, and hotels that meet the jurisdiction’s signing rules.