State Road 231 (SR 231), locally known as Dr. Martin Luther King Jr. Avenue and SW 6th Avenue, is a north-south discontinuous route running through Union County, Bradford County, and Alachua County, Florida.
|Maintained by FDOT|
|Length||6.317 mi (10.166 km)|
|South end||SR 235 near LaCrosse|
| SR 18 in Brooker
Reception and Medical Center near Lake Butler
|North end||SR 238 in Lake Butler|
State Road 231 begins near LaCrosse at the intersection with SR 235 and County Road 231 (former SR 231). From there it heads north, cosigning with SR 235, across the Santa Fe River into Bradford County and Brooker. At the junction with SR 18, state maintenance ends and the road becomes County Road 231, with County Road 235 cosigning. CR 235 leaves the road approximately two miles (3.2 km) north of the junction. The route continues north into Union County, passing CR 231A, and regains state road status near SW 78th Street and the Florida Department of Corrections Reception and Medical Center. The road then heads into Lake Butler, crossing SR 121 and ending at SR 238 several blocks short of SR 100.
SR 231 originally terminated at SR 121 roughly six miles (9.7 km) south of its current terminus. The former relinquished segment is signed as County Road 231.
A second piece of CR 231 fills the gap in SR 231 between Brooker and south of Lake Butler. East of Brooker is a third piece looping south off County Road 18 that does not line up with the others, yet was also once known as SR 231.
|Alachua||Gainesville||0.000||0.000||SR 121 – Gainesville, LaCrosse|
|||3.0||4.8||Northwest 156th Avenue (CR 340 east)|
|||6.018||9.685||SR 235 south – LaCrosse||south end of state maintenance; south end of SR 235 overlap|
|Bradford||Brooker||9.397||15.123||CR 18 east (Charlotte Avenue) – Graham, Starke||south end of SR 18 overlap|
|9.596||15.443||SR 18 west – Worthington Springs||north end of SR 18 overlap; north end of state maintenance|
|||10.0||16.1||Bloxham Street (CR 235A south)|
|||11.5||18.5||CR 235 north||north end of CR 235 overlap|
|Union||||16.1||25.9||CR 231A west|
|||17.1||27.5||Southwest 73rd Street||South end of state maintenance|
|Lake Butler||19.6||31.5||SR 121 (Southwest 6th Street)|
|19.8||31.9||SR 238 (Southwest 2nd Street / Southwest 6th Avenue) – Providence|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|