 East of the Metro East region, I-70 meets US 51 in Vandalia and both I-57 and US 45 in Effingham.Like all Interstate highways, I-70 is a part of the National Highway System for its entire length in Illinois.I-70 enters Illinois from St. Louis by crossing the Mississippi River on the four lane Stan Musial Veterans Memorial Bridge into the village of Brooklyn in St. Clair County.