High Quality Content by WIKIPEDIA articles! Iowa Highway 3 is a state highway that runs from east to west across the state of Iowa. Highway 3 is the longest state highway in Iowa, at 327.81 miles (527.56 km) long. Iowa 3 begins at the South Dakota state line where it continues as South Dakota Highway 50 and ends at an interchange with U.S. Route 61 / U.S. Route 151. It is designated the American Veterans Memorial Highway for its entirety. It is located approximately halfway between Interstate 80 and Interstate 90.