Interstate 35 (I-35) is an interstate highway running north-south in the central United States. It stretches from Laredo, Texas at the Mexican border to Duluth, Minnesota at Minnesota State Highway 61 (London Road). Many interstates used to have splits or spurs indicated with suffixed numbers, but I-35 is the only one that still has such divisions. In two stretches, the highway splits into Interstate 35E (Dallas and St. Paul) and Interstate 35W (Fort Worth and Minneapolis). In both cases, the exit numbers follow I-35E, but everything else gives the two routes equal status.
In Austin, Texas, elevated express lanes were constructed on either side of the original freeway. Prior to this expansion, this section included an at-grade railroad crossing, which is extremely unusual for a freeway.
I-35 splits up into I-35W and I-35E in the Dallas/Fort Worth, Texas area. The official mile markers follow I-35E through Dallas -- I-35W, which is 85 miles in length, carries its own mileage from Hillsboro to Denton, as though it were an x35 loop.
I-135, which branches off in Wichita, Kansas, is 95 miles (153 km) long. It carried the designation I-35W until the 1980s, despite never rejoining the main line of I-35. It terminates in Salina, Kansas at the intersection with Interstate 70 (though the controlled-access freeway continues north as US 81).
At Medford, Minnesota, the on/off ramps lead to roundabouts rather than standard cross intersections. This is the first site in the state linked to a major highway to use roundabouts.
Interstate 335 was planned as an additional bypass of the Twin Cities; that road was never built.
I-35 splits again into I-35W and I-35E in the Minneapolis/Saint Paul, Minnesota area. At one sharp turn in I-35W near the junction with I-94, it is advised to slow to 35 mi/h (56 km/h) (although many drivers are able to maintain the speed limit of 55 mi/h (88 km/h)). Additionally, it is not possible to go from westbound I-94 to northbound I-35W or from southbound I-35W to eastbound I-94 without resorting to surface streets.
