Below are the four state capitals not directly served by the Interstate System:
Jefferson City, Missouri
Pierre, South Dakota
Missouri, Kansas, and Pennsylvania have claimed the title of first Interstate Highway. On August 13, 1956, Missouri was awarded the first contract under the Federal Aid Highway Act of 1956. Kansas says road paving started September 26, 1956. On October 1, 1940, 162 miles of the Pennsylvania Turnpike now designated I‑70 and I‑76 opened between Irwin and Carlisle.
Carson City, Nevada is the most recent state capital to become directly served by the Interstate System. The new I-580 freeway between Reno and Carson City running north and south opened in August 2012.
Inspired by the network of high-speed roads he saw in Germany during World War II, Dwight D. Eisenhower championed the passing of the Federal-Aid Highway Act of 1956. The law funded the first 41,000 miles of paved glory that made up the early U.S. interstate system, which now boasts 46,876 miles and runs through all 50 states.
Check out more facts about the U.S. Interstate System from MentalFloss.com.