The highway provides a more direct route through Downtown Kansas City than the older mainline I-70 and avoids the sharp turn (and reduced speed limit) of the latter at the west end of the Intercity Viaduct.

The freeway then crosses the Kansas–Missouri state line and enters Kansas City, Missouri.

The road then has an interchange with I-35 just before passing beneath the Kansas City Convention Center.

[13][14] On May 20, 1997, sections of I-670 and I-35 in Downtown Kansas City were closed for the filming of a music video for the U2 song "Last Night on Earth".

The closure, which was criticized by a local American Automobile Association official, caused some traffic congestion and was the subject of 50–60 complaints to the city government.