U.S. Route 166

U.S. Route 166
US 166 highlighted in red
Route information
Auxiliary route of US 66
Maintained by KDOT and MoDOT
Length	164.159 mi (264.188 km)
Existed	1926–present
Major junctions
West end	US-81 in South Haven, KS
Major intersections	I-35 / Kansas Turnpike east of South Haven, KS US-77 in Arkansas City, KS K-15 in eastern Cowley County, KS K-99 south of Sedan, KS US-75 north of Caney US-169 in Coffeyville, KS US-59 in Chetopa, KS US-69 west of Baxter Springs, KS US 69 Alt. in Baxter Springs, KS US-400 east of Baxter Springs, KS
East end	I-44 / US 400 near Joplin, MO
Location
Country	United States
States	Kansas, Missouri
Counties	KS: Sumner, Cowley, Chautauqua, Montgomery, Labette, Cherokee MO: Newton
Highway system
United States Numbered Highway System List Special Divided
Kansas State Highway System Interstate US State Spurs
Missouri State Highway System Interstate US State Supplemental
← K-163 KS → K-167 ← Route 165 MO → Route 168

U.S. Route 166 (US 166) is a 164-mile (264 km) east–west United States highway. This route and US 266 are the only two remaining spurs of historic U.S. Route 66 (which was decommissioned in 1985), since US 666 was renumbered to US 491 in 2003.

US 166 meets the old route of US 66, now designated US 69 Alternate, in Baxter Springs in the southeast corner of Kansas.