U.S. Route 50 in Illinois

After US 50 and I-255 leave Mehlvile and enter Columbia, they then run concurrently with Illinois Route 3 (IL 3), as well as the Great River Road, at a directional T interchange (exit 6). At a trumpet interchange (exit 10), IL 3 and the Great River Road leave the freeway. Further northeast, they meet IL 157 at a parclo interchange with five ramps, Mousette Lane at a diamond interchange, IL 15 at a cloverleaf interchange, and State Street at a four-ramp parclo interchange. At the next interchange, US 50 moves off I-255 to I-64 at a cloverleaf interchange with collector–distributor lanes. Once US 50 moves onto I-64, it continues eastward. They meet IL 157 at a four-ramp parclo, IL 159 at a six-ramp parclo, and a few other interchanges before they reach another cloverleaf. At that point, US 50 turns north from I-64, briefly overlapping IL 158 until US 50 turns east.

In Lebanon, US 50 turns north and then east via IL 4. As it continues eastward, it remains a two-lane undivided highway. North of Trenton and Breese, each part of US 50 briefly becomes a four-lane divided highway with one diamond interchange each (one with IL 160 and one with Jamestown Road respectively). Each section reverts to an undivided highway.

In Carlyle, US 50 turns south and then back east (overlapping IL 127). In Sandoval, it turns north and then back east again (overlapping US 51). In Salem, it meets I-57 west of downtown and IL 37 within downtown.[2]

As US 50 meanders eastward, it eventually reaches US 45 north of Flora. At that point, US 45 runs concurrently with US 50. Then, it branches off south from US 50. Further east, it reaches Salem. At that point, IL 250 begins west of Noble and then travels northeast to downtown Noble and Olney. As US 50 intersects IL 130 south of Olney, IL 250 overlaps US 50.

Just north of Sumner, IL 250 moves off south to Sumner and Bridgeport. Just northwest of Lawrenceville, US 50 Business begins; it serves downtown Lawrenceville. Across the Embarras River, US 50 reaches a one-quadrant interchange with IL 1.

East of Lawrenceville, US 50 becomes a four-lane divided highway for the rest of its run in the state. It meets US 50 Business at an incomplete interchange, a diamond interchange, and IL 33 at a modified diamond interchange before exiting Illinois.[2]