It was originally proposed by Missouri as I-144, but the road was a beltway (or part of one), so the American Association of State Highway and Transportation Officials (AASHTO) assigned it the number I-244.

In Missouri, I-270 diverges from at I-55 as a 10-lane freeway heading west of I-55's route but still maintaining I-55's tendency to travel northward.

[3] Congestion in this area is severe to the point the Missouri Department of Transportation (MoDOT) has spent millions on various traffic control improvements since the 1990s.

One of the safety improvements is a "double white line" that motorists are not permitted to cross (violation of that could lead to a fine of $500) that is located at the exits for I-70 in the northbound lanes.

Since Dunn Road handles two-way traffic, this has become a safety and congestion issue that MoDOT wants to address in the near future.

[4] At Lilac Avenue, I-270 constricts to four lanes as it crosses the Mississippi River on the New Chain of Rocks Bridges.

Once it passes IL 111, the speed limit increases to 65 mph (105 km/h) as the highway briefly becomes six lanes again with the junction with I-255.

[citation needed] A major accident and fire from a FedEx Ground truck between the Route 367 and Lilac Avenue exits on October 28, 2002, forced detours and lengthy delays.

[11] A five-mile (8.0 km) section of I-270 between I-44 and Manchester was widened to five lanes in each direction, with work taking place between 2012 and 2013.

MoDOT has also identified the need of improving the I-270 corridor in northern St. Louis County, which could cost in the range of $200 million.

[16] The agency planned to widen the freeway from US 67 to Route 367 and rebuild every interchange (except I-170) and overpasses in this section.