with U.S. Route 31E for its first in Kentucky, US 231/31E enters the state from Sumner County, Tennessee, and into Allen County. The two routes separate on the west side of Scottsville after the KY 100 junction. US 231 turns northwestward into a four-lane highway on its way into Warren County, and into Bowling Green. Just before entering the city, US 231 crosses the southern terminus of KY 9007, a short connector providing access to I-65 and I-165. US 231 crosses I-165 on the northwestern edge of the city. US 231 reaches Butler County to cross the I-165 for a second time, and runs concurrently with KY 79 into Morgantown. KY 70 joins in on the concurrency as US 231, KY 79, and KY 70 cross the Green River. Both state routes separate in the Aberdeen area before crossing the I-165 for a third and final time before entering Ohio County. US 231 meets U.S. Route 62 in the Beaver Dam/Hartford area after crossing the Wendell H. Ford Western Kentucky Parkway on the south side of Beaver Dam. US 231 goes further north into Daviess County to join up with US 60 to bypass Owensboro. US 60 splits from US 231 before leaving the state via the William H. Natcher Bridge going into Spencer County, Indiana.
Alternate names
U.S. 231 has several alternate names throughout its course in Kentucky. They include:
In Kentucky, US 231 was originally signed as Kentucky Route 71, one of many charter routes of Kentucky's statewide system of highways when it was established in 1929. KY 71 originally ran from downtown Scottsville to downtown Owensboro. Portions of the original KY 71 in Butler County was rerouted to a bridge over the Green River in the early 1950s, replacing the Morgantown Ferry. In 1952, US 231 replaced the alignment of KY 71 in its entirety as it was extended to include several routes into Tennessee, Kentucky, and Indiana from Montgomery, Alabama. In August 1999, US 231 in Bowling Green was rerouted onto KY 880 from the Scottsville Road intersection to the Morgantown Road intersection on the northwest side of town. The former alignment of US 231 into downtown Bowling Green was redesignated as US 231 Business. In the 2002-03 fiscal year, US 231 in Daviess County was rerouted onto the then-new William H. Natcher Bridge northeast of Owensboro. It previously followed the current KY 2155 and KY 2262 onto the Owensboro Bridge in downtown Owensboro into Spencer County until the opening of the Natcher Bridge. The stretch of US 231 from the Natcher Parkway interchange to Bell Street in Morgantown was widened to include a center lane for turning in 2013-2014.
In late May 2017, the KYTC raised the speed limit of US 231 from near Scottsville to the near the Drakes Creek bridge south of Bowling Green from the original to. This makes this stretch of US 231 the second section of a four-lane divided highway with unlimited access in the region with a 65 mph speed limit, the first being US 68/KY 80 from I-24 in Trigg County to the I-165 Exit 5 interchange at Bowling Green.
