U.S. Route 20 in Iowa

U.S. Highway 20
Route information
Maintained by Iowa DOT
Length:	301.429 mi (485.103 km)
Existed:	1926 – present
Major junctions
West end:	I-129 / US 20 / US 75 at South Sioux City, NE
	I-29 in Sioux City US 75 at Sioux City US 71 near Early US 169 near Fort Dodge I-35 near Williams US 69 near Iowa Falls I-380 / US 218 in Waterloo US 52 / US 61 / US 151 in Dubuque
East end:	US 20 at East Dubuque, IL
Location
Counties:	Woodbury Ida Sac Calhoun Webster Hamilton Hardin Grundy Black Hawk Buchanan Delaware Dubuque
Highway system
United States Numbered Highway System List Special Divided Replaced Iowa Primary Highway System Interstate U.S. State Secondary Scenic ← US 18 Iowa 21 →

U.S. Highway 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 and U.S Route 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. The state of Iowa is in the process of upgrading US 20 into a four-lane divided highway for its entire length in Iowa.

US 20 enters Iowa on the Sergeant Floyd Memorial Bridge, which also carries I-129 and US 75, over the Missouri River. Almost immediately upon landing in Iowa, there is an interchange with I-29, at which I-129 ends. Continuing east, US 20 and US 75 run together around the southern and eastern sides of Sioux City. The two routes split and US 20 continues to the east. US 20's business loop of Sioux City begins at the US 75 interchange as well.

East of Sioux City, U.S. Highway 20 continues as an expressway until Moville. From there, it is a rural, two-lane highway with only a short expressway segment just south of Holstein, that is briefly concurrent with U.S. Route 59. From US 59, it is about 18 miles (29 km) until US 20 has another four-lane segment, starting about one mile west of an interchange with U.S. Route 71 and Iowa Highway 471, just north of Early. This final stretch of two-lane road will be upgraded to four-lane between 2016 and 2018. From this point until an interchange with Iowa Highway 4 northwest of Rockwell City is the newest section of four-lane, which opened in November 2012. This new roadway passes to the north of Sac City and Lytton, and has another interchange with the realigned route of U.S. Route 71 northeast of Sac City, but mostly has at-grade intersections, including County M54 into Sac City and N28 into Lytton.

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Wikipedia