U.S. Route 20 in Iowa

U.S. Highway 20
U.S. Highway 20
	US 20 highlighted in red
Route information
	Maintained by Iowa DOT
Length	300.270 mi (483.238 km)
Existed	1926–present
Major junctions
West end	I-129 / US 20 / US 75 at South Sioux City, Neb.
	I-29 in Sioux City; US 75 at Sioux City; US 71 near Early and Sac City; US 169 near Fort Dodge; I-35 near Williams; US 65 near Iowa Falls; I-380 / US 218 in Waterloo; US 52 in Dubuque; US 61 / US 151 in Dubuque;
East end	US 20 at East Dubuque, Ill.
Location
Country	United States
State	Iowa
Counties	Woodbury; Ida; Sac; Calhoun; Webster; Hamilton; Hardin; Grundy; Black Hawk; Buchanan; Delaware; Dubuque;
Highway system
	United States Numbered Highway System; List; Special; Divided; Iowa Primary Highway System; Interstate; US; State; Secondary; Scenic;

U.S. Highway 20 (US 20) in Iowa is a major east–west artery which runs across the state, separating the northern third of Iowa from the southern two-thirds. It enters Iowa from Nebraska, concurrent with Interstate 129 (I-129) and US 75, crossing the Missouri River at Sioux City. US 20 runs in a more-or-less straight line across Iowa, paralleling 42° 27' N. It leaves Iowa in Dubuque by crossing the Mississippi River into Illinois. Since October 2018, US 20 is a four-lane divided highway for its entire length in Iowa.