Iowa Highway 143 (Iowa 143) is a north–south state highway northwestern Iowa. The highway is 12 miles (19 km) long. The route was designated in 1926 when its original number, Primary Road No. 75 was reused for U.S. Highway 75. It was originally a short spur route into Marcus, but was extended north to Iowa 10 in 1938. From 1941 to 1961, the highway extended south from Iowa 3 / Iowa 5 to the Cherokee–Woodbury county line.