South Portsmouth and enters Ohio at Portsmouth. Since 1999, the entire Kentucky portion is a four-lane divided highway; in some of the larger cities, there are additional traffic lanes present in both directions. In northeastern Kentucky, from the I-64 junction north into Ohio, some sections are four-lanes undivided, with a double yellow line instead of a median. These are the oldest four-lane sections of US 23 in Kentucky which were upgraded in 1950s and 1960s before divided highways became the design standard. They can be found on US 23 in the cities of Catlettsburg, Ashland, and Russell. Ohio The majority of US 23 in Ohio is a divided expressway, with the exception of downtown Columbus and the portion of the route between Carey and US 20 east of Perrysburg. US 23 crosses the Ohio River from Kentucky and enters Portsmouth and passes through the towns of Lucasville, Piketon, Waverly, Chillicothe, and Circleville, before reaching Columbus. The highway then mostly follows High Street in Columbus, which was the original route. However, it now bypasses the central business district and northern Columbus neighborhoods by following the one-way pairing of 4th Street (northbound) and 3rd/Summit Street (southbound) between the downtown area and Hudson Street, and Indianola Avenue north before returning to its original course on High Street at Morse Road. US 23 then follows High Street northbound from Columbus, going through Worthington, passing the village of Lewis Center, entering Delaware at the Cheshire Road intersection. After US 23 intersects the northern terminus of SR 315 and passes a retail district, it becomes a limited-access freeway, bypassing downtown Delaware, before resuming as an expressway with at-grade crossings north of the city. At Waldo, US 23 again becomes a freeway. It continues as a freeway throughout most of Marion County, then resumes at-grade crossings with a mix of some freeway-style junctions which are otherwise signalized after the Morral interchange. US 23 runs concurrently with divided SR 15 until it takes a different route at the Carey exit. SR 15 continues on to Findlay and is designed to allow most traffic to bypass the northern stretch of US 23 by offering a fast connection to I-75. US 23 continues north through Carey, Fostoria, and Risingsun. West of Woodville, US 23 intersects US 20, where it has an overlap for several miles. US 23 then joins I-75 near Perrysburg, then follows I-475 around the west side of