Illinois Route 13 (IL 13) is a major east–west state route in southern Illinois. Illinois 13 has its western terminus at Centreville at Illinois Route 157 and its eastern terminus at the Kentucky state line and the Ohio River, at Kentucky Route 56. This is a distance of . Route description Centreville to Carbondale Illinois 13 runs southeast from the St. Louis, Missouri area to Carbondale. It is the main highway between these two cities. Starting in Centreville, IL 13 begins at the IL 157/IL 163 junction. Immediately, IL 13 travels southeast along IL 157. At the next junction, IL 157 branches off northeast. At this point, IL 13 largely parallels the IL 15 expressway. In Belleville, IL 13 meets IL 15 at an incomplete parclo. Continuing southeast, IL 13 largely serves Belleville's business district, unlike the expressway. It then meets IL 15 again and IL 158 at a dumbbell interchange. After that, IL 13 runs concurrently with IL 158. They then intersect IL 159 above Richland Creek. They soon separated from each other. IL 13 turns southeast to connect and then run concurrently with IL 15. Both routes then turn south towards Freeburg along a four-lane divided highway. At the village limit of Freeburg, the road downgrades into a four-lane undivided highway. Then, the road downgrades into a three-lane roadway in the village. IL 15 then breaks away eastward from IL 13. IL 13 continues southward towards New Athens. Just west of New Athens, as IL 13 curves southeastward, it intersects IL 156. After that, it crosses a bridge over the Kaskaskia River. It then passes through Lenzburg, Marissa (where IL 4 starts to follow along IL 13), Whiteoak, Tilden (where IL 13 branches eastward away from IL 4), Coulterville (where IL 153 briefly runs concurrently with IL 13), Swanwick, Winkle, and Pinckneyville. In Pinckneyville, IL 13 turns east along IL 154. At the Perry County Courthouse and the Perry County Jail, IL 13 turns south, leaving IL 154 and joining IL 127. Both IL 13 and IL 127 then pass through the Pyramid State Recreation Area, Pyatts (where they intersect IL 152), and Vergennes. Then, IL 4 intersects IL 13 once again. In Murphysboro, IL 149 joins the concurrency. Continuing south, IL 13 turns eastward, leaving the concurrency. At this point, IL 13 skirts the northern edge of the Shawnee Hills and the Shawnee National Forest. It then