U.S. Route 166 (US 166) is an east–west United States highway that runs across southern Kansas. It is a regional connector of roughly 164 miles (264 km) that links rural communities, agricultural areas and smaller urban centers. US 166 is notable for its historical connection to the famous U.S. Route 66 and for remaining in service after the decommissioning of the original Route 66.

Route and characteristics

The corridor followed by US 166 is predominantly two-lane roadway outside of towns, with occasional short divided or multi-lane stretches through larger communities. It parallels the southern edge of Kansas, providing direct access to county seats and serving local freight, farm-to-market travel and commuter movements. While it is not an interstate, the highway connects with several major national and state routes that facilitate longer-distance travel and commerce.

History and relationship to Route 66

US 166 was created as part of the U.S. numbered highway system and has long been identified as one of the branch routes associated with the historic U.S. Route 66. When US 66 was officially removed from the U.S. Highway System in 1985, several of its spur or child routes, including US 166 and US 266, continued to carry their existing numbers. Changes elsewhere in the network—such as the renumbering of US 666 to US 491 in 2003—have left US 166 as one of the surviving routes with a numerical link to the original Route 66 family.

Uses and local importance

For residents and businesses in the region, US 166 is an essential element of mobility. It supports agricultural transport, regional retail and service access, school and postal routes, and tourism to historic and recreational sites. Parts of the highway attract travelers interested in the legacy of old Route 66 and in small-town Americana, while other segments function primarily as pragmatic transport links.

Notable facts and intersections

  • US 166 meets a former alignment of Route 66 — now part of US 69 Alternate — in Baxter Springs: Baxter Springs, in the southeast corner of Kansas.
  • It remains one of the surviving numbered branches associated with the historic Route 66 network.
  • The highway traverses largely rural territory and connects several county seats and small towns that rely on it for economic links to larger corridors.

Travelers using US 166 should expect a mixture of rural driving conditions and short urban stretches. Its value is strongest at the local and regional levels, where it continues to bind southern Kansas communities and preserve a living connection to the era of numbered U.S. highways.