Florida Edit

In Florida, US 231 is paired with unsigned State Road 75. The southern terminus is at Business US 98 (unsigned State Road 30) in downtown Panama City. The highway is carried by Harrison Avenue until its intersection with US 98. Continuing north, US 231 passes through Youngstown, Fountain, Alford, Cottondale, and Campbellton before entering Alabama. Major intersections include Business US 98, US 98, SR 77, SR 20, Interstate 10, US 90, SR 73, SR 273, and SR 2.

Alabama Edit

In Alabama, US 231 is paired with unsigned State Route 53 from Huntsville to Dothan.

The route passes through mostly straight terrain between the Tennessee state line and Meridianville, which is home to its junction with Bob Wade Lane, which eventually becomes AL-255.

The route descends down a slight hill and enters Huntsville. It becomes a freeway (Memorial Parkway). It junctions with U.S. 72 east/ Sparkman Drive. After a short concurrency with U.S. 72, it splits off onto University Drive. The route almost immediately junctions with Interstate 565. It then junctions with a two-part interchange (Clinton Avenue/U.S. 431 South/AL-53 North; Governors' Drive). Here, it gains AL-53 and loses U.S. 431. The route continues south as a freeway until it reaches a specific point when it becomes a four-lane divided highway. It passes by Redstone Arsenal Gate 3's access road, Hobbs Road. The route continues south until it reaches the Clemont C. Clay Bridge. It promptly crosses the Tennessee River into Morgan County.

The route eventually junctions with AL-36. It climbs up a mountain into Union Hill. While climbing, the route makes a slight curve from the southwest to the southeast that is easily noticeable on road maps. It then passes through Morgan City and enters Marshall County.

The route heads through mountainous terrain to Arab, which is home to its junction with AL-69. This junction is a diamond interchange and is directly above the line with Cullman County.

There are no major junctions in Cullman County.

It eventually crosses the line into Blount County. The road turns to the southwest and junctions with AL-67. It quickly junctions with U.S. 278. Eventually, the route reaches Blountsville, which is home to Spring Valley Beach, a water-park with a notable set of water slides. Past Blountsville, the route junctions with AL-79 North. It reaches Cleveland and splits off from AL-79, which continues on its right of way to Birmingham. U.S. 231 then junctions with AL-160 West, which continues on its next right-of-way. It passes through mountains until it reaches Oneonta, which is home to its junction with AL-75. The route climbs up a high hill and descends it, now crossing into St. Clair County.

The route eventually junctions with U.S. 11 and then I-59. It enters Ashville. It junctions with AL-23 and U.S. 411/AL-25 North. After a moderate concurrency with the two routes, U.S. 411 and AL-25 turn southwest towards Leeds. U.S. 231 heads directly south towards Pell City. The route heads through extremely hilly terrain as a two-lane and three-lane road. It reaches Coal City and junctions with AL-144. It continues down through the same terrain to I-20. It reaches U.S. 78 and then AL-34.

U.S. Route 231 reaches Shelby County. It parallels the Coosa River as it reaches Vincent, which is home to its next junction with Alabama State Route 25. They continue south to Harpersville. Alabama State Route 25 junctions with U.S. 231 for the last time here as U.S. 231 turns onto U.S. Route 280.

The routes then cross into Talladega County. After a long journey to Sylacauga, the route turns off of U.S. 280 at its junction with AL-21, which is a Diamond Interchange. The route enters Coosa County near this point.

In Coosa County, the route junctions with AL-22 in Rockford. It then enters Elmore County after a long journey south.

In Elmore County, there are no major junctions until it reaches AL-9. This point is the line with the city of Wetumpka. The route junctions with AL-14 and AL-170 north of the city. Within the city, the routes (Alabama State Route 9, U.S. 231, and Alabama State Route 21) junction with AL-111. The routes then enter Montgomery County.

The routes junction with AL-152/Northern Boulevard, a half-beltway around Montgomery. The routes join the half-beltway. AL-152 ends at this point, though. The routes turn from east to south and junction with Atlanta Highway. The routes junction with I-85 and gain U.S. 80. The routes turn to the west. U.S. 231 and U.S. 82 turn to the south. Alabama State Route 21, U.S. Route 80, and Alabama State Route 9 continue onward with U.S. 82 west to I-65, U.S. 331, and U.S. 31. U.S. 82 and U.S. 231 continue onward to Pike Rd, which is not a road, but a town. South of here, U.S. 82 turns off of US. 231 and U.S. 231 continues onward on a four-lane divided highway into Pike County.

There are no major junctions in Pike County until U.S. Route 231 reaches Troy. Here, the route junctions with U.S. Route 29, AL-10 west, and AL-87. U.S. 231 continues southeast to Brundidge, which is home to its junctions with Alabama State Route 10 east, AL-93, and AL-125. The route then cuts a corner of Coffee County.

There are no major junctions in Coffee County.

The route then enters into Dale County. The route junctions with AL-123 and AL-51 in the far-vicinity of Ariton, Alabama. The route reaches Ozark, which is home to its junctions with AL-27, AL-249, and once again Alabama State Route 123. In Midland City, the route junctions with AL-134 and AL-605. The route has officially entered the Dothan Metropolitan Area.

In Houston County, the route has no major junctions until it reaches the Ross Clark Circle, which is U.S. 84 and AL-210. This same junction is the junction with U.S. 231 Bus. and the point where Alabama State Route 53 ultimately leaves its state-wide concurrency with U.S. 231. The route turns south onto the Ross Clark Circle and heads to the junction with U.S. 84 Bus. East/U.S. 84 West. Here, U.S. 84 leaves the Ross Clark Circle. It then continues southeast until it reaches AL-52. AL-52 does not have a business route, unlike U.S. 231 and U.S. 84. The route turns to the full east and junctions with U.S. Route 431 once again, for the first time since Huntsville, Alabama, alongside U.S. 431 Bus.. This junction marks the southern terminus of U.S. 431. The route turns south off of the Ross Clark Circle with AL-1. It then heads south for the Florida state line. The route junctions with AL-109 in Hodgesville and Alabama State Route 605 once again in Madrid, before finally crossing the state line into Campbellton, Florida.

Tennessee Edit

US 231 enters Tennessee from Alabama in a concurrency with US 431 until it reaches Fayetteville. North of there it runs through Shelbyville and later passes through the eastern part of the Nashville metro area, passing through the cities of Murfreesboro, and Lebanon. By the time it reaches Bethpage, it joins U.S. Route 31E in another concurrency to the northeast before finally crossing the Kentucky State Line north of Westmoreland. The route is approximately 121 miles (195 km) from Tennessee's northern border to its southern border.

Kentucky Edit

US 231 parallels Interstate 65 before reaching Bowling Green. From Bowling Green, US 231 closely parallels the William H. Natcher Parkway until it reaches Owensboro. At Owensboro, US 231 joins US 60 (also known as the Wendell H. Ford Expressway) around the city's east side, which it then follows to just north of Maceo. US 60 then leaves toward the east while US 231 turns to the north, leaving the state via the William H. Natcher Bridge across the Ohio River.

A portion of the Owensboro-area route is relatively new; in 2014, a new section from Kentucky 54 to Kentucky 2830 opened, bypassing the former bypass route. Part of that former route has been renumbered as Kentucky 603. The remainder, south of 603, is partly a dead-end city street and an abandoned lane that will eventually become part of the David Adkisson Greenbelt trail.

Indiana Edit

In Indiana, US 231 has the distinction of being the state's longest continuous highway. It covers approximately 297 miles (478 km) in the Hoosier State. US 231 passes through the towns of Dale, Huntingburg, Jasper, and Loogootee before reaching Bloomfield. In Bloomfield, US 231 passes Shawnee Field, a local airport. US 231 slices through central Indiana before reaching Lafayette, where it runs just south of Purdue University. Next it winds northwest along Interstate 65 and then it splits off and terminates at US 41.

Indiana's Major Moves program, which derives its funding from the lease of the Indiana Toll Road to private interests, has made it possible for the state to build many new miles of roadway throughout the state. As part of this program, US 231 is currently being updated to a new-terrain four-lane highway from the Indiana-Kentucky border through Spencer County to Interstate 64. This segment of US 231 has been named the Abraham Lincoln Memorial Parkway.

As of April 2011, the Lincoln Parkway is complete from the Kentucky line to the interchange at I-64 and the bypass of Dale at the northernmost end of the project. It is a fully operational partial cloverleaf and the previous two-lane 231 overpass has been demolished. It has been replaced by a new four-lane overpass.

The section from SR 162 to Indiana State Highway 70 near Chrisney was the last to be opened, after a ribbon-cutting ceremony on March 15, 2011, much sooner than the original July 2011 projected date.

In addition to the Spencer County project, a four-lane bypass of the Dubois County cities of Huntingburg and Jasper is also in the planning stages, but funding has not been secured. A firm timetable for construction has yet to materialize.