Route 370

Missouri Route 370 is a 13 mile limited-access highway running between St. Peters and Bridgeton through the Missouri River Bottoms north of St. Charles. The freeway was constructed between 1988 and November 20, 1996 at a cost of $250 million.¹

The Discovery Bridge along Route 370 replaced the 88-year old Missouri River Bridge of Highway 115, which closed on December 29, 1992.² Route 370 initially opened between Interstate 270 at Bridgeton and Third Street in St. Charles on December 16, 1992 as a new alignment of Route 115. Next was the extension west to Mueller Road and a temporary end there. The Mueller Road exit closed when the freeway grew by another mile west to Elm Street (Exit 5) on November 3, 1994.³

July 31, 1996 saw another 2.5 miles of freeway open between Elm Street and Harry S. Truman Boulevard (Exit 2).⁴ The final stretch (Spencer Road segment) to open was the 1.8 mile link between Truman Boulevard and Interstate 70 at St. Peters.⁵ The west end interchange of the Route 370 freeway replaced a set of weigh stations along the I-70 mainline.³

Missouri Route 370 replaced Route 115 on the 1992-freeway from Interstate 270 to Route 94 in St. Charles on April 1, 1993. Route 115 was truncated east to Interstate 70 at Berkeley (Exit 238A), leaving Cypress Road and Natural Bridge Road west from St. Louis Lambert International Airport (STL) as Route B. St. Charles Rock Road west from Pennridge Drive to Missouri Bottom Road was redesignated as Route A, which was later decommissioned. The renumbering of Route 115 was done because the freeway portion did not connect with the rest of the route and to avoid driver confusion.⁶

Missouri Route 370 Guides

• East
• West

Connect with:
Interstate 70
Interstate 270

Page Updated 11-27-2013.