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 | ![]() ![]() ![]() | |||
East end | ![]() | |||
Location | ||||
Country | United States | |||
State | Iowa | |||
Counties | ||||
Highway system | ||||
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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.