at the interchange with I-20 in Jackson. The highway then runs through Jackson, intersecting US 80. Outside Ridgeland, it passes under I-55 as it continues northeast. It continues through Canton, Pickens, Goodman, and Durant. The highway continues to run along I-55, intersecting US 82 in Winona and US 278 in Batesville. The route passes under I-69 before entering Tennessee. The Mississippi section of US 51 is defined at Mississippi Code Annotated § 65-3-3. Tennessee US 51 enters Tennessee from Mississippi and travels through Memphis. It intersects I-55 and then I-240 before intersecting US 78. It then runs concurrently with US 79 before intersecting I-69. As it exits Memphis, it intersects I-40 and heads northeasterly. In Dyersburg, it runs concurrently with US 412 for a half a mile before intersecting I-155's eastern terminus. US 51 then continues northeasterly before entering Kentucky. US 51 between Memphis and Kentucky is planned on running concurrently with I-69. Kentucky US 51 enters Kentucky at Fulton, running concurrently with I-69 and continues northward through the towns of Clinton, Bardwell and Wickliffe to the Ohio River. The route intersects and runs concurrently with US 62 before separating from it in Cairo. Along the way it also intersects US 60. The route then enters Illinois before running concurrently with I-57. Illinois US 51 enters Illinois from Kentucky at the city of Cairo. The route heads northward to a village near Cairo called Mounds, and shares the pavement with I-57, following it for to Dongola, before splitting and heading north. The route remains two lanes from Dongola to just before Assumption with the exception of a section between Centralia and I-64. North of Assumption, US 51 becomes an expressway to Decatur. In Decatur, US 51 follows I-72 to bypass town. US 51 leaves I-72 after , and heads north to Bloomington–Normal as an expressway. At Bloomington–Normal, US 51 follows I-74 for a mile, then I-55 for , before following I-39 for . US 51 follows I-39, intersecting I-80 and I-88 along the way. The highway also follows US 20 south of Rockford (while still following I-39). I-39/US 51 joins I-90, making US 51 one of the only toll roads in Illinois that is a U.S. Highway. US 51 exits I-39/I-90 just a mile south of the Wisconsin state line. US 51 follows Illinois Route 75 (IL 75) west to the intersection of IL 251, then turns north through South