Kansas

I-635 begins at I-35 in Johnson County near Shawnee, Kansas, at exit 1A. There is a parclo interchange with Merriam Drive at exit 1B almost immediately after its terminus. It then enters Wyandotte County and Kansas City, Kansas. There is a diamond interchange with Shawnee Drive at exit 1C and a parclo interchange with Metropolitan Avenue at exit 1A upon entering the Argentine neighborhood. There is an interchange with K-32/Kansas Avenue at exit 3 and then crosses the Kansas River into central Kansas City, Kansas. Immediately after crossing the river, there is an interchange with I-70 at exits 4A and 4B. There are several interchanges further north, including State Avenue (exit 5), Parallel Parkway (exit 6), and Leavenworth Road and North 38th Street (exit 7). The last public interchange before entering Missouri is K-5. A private maintenance facility crossing at grade exists between this exit and the Missouri River.

Missouri

Like I-435, I-635's mileposts do not reset after crossing into Missouri.

I-635 crosses the Missouri River from Kansas into Platte County and the city of Riverside, Missouri. There is an interchange with Horizons Parkway at exit 9 and then US 69 at exit 10. US 69 briefly runs concurrently with I-635 north before exiting at the interchange with Route 9 (exits 11A and 11B). I-635 runs a few more miles north, then terminates at I-29/US 71 at exits 12A and 12B.