U.S. Route 20 in Iowa

U.S. Highway 20
US 20 highlighted in red
Route information
Maintained by Iowa DOT
Length	300.270 mi[1] (483.238 km)
Existed	1926–present
Major junctions
West end	I-129 / US 20 / US 75 at South Sioux City, Neb.
Major intersections	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
← US 18 → Iowa 21

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.