- Interstate 35 (I-35) is a major Interstate Highway in the central United States. As with most primary Interstates that end in a five, it is a major cross-country, north–south route. It stretches from Laredo, Texas, near the Mexican border to Duluth, Minnesota, at Minnesota State Highway 61 (MN 61, London Road) and 26th Avenue East. The highway splits into I-35E and I-35W in two separate places, the Dallas–Fort Worth metroplex in Texas and at the Minnesota twin cities of Minneapolis–Saint Paul.