U.S. Route 50 in Ohio partially coincident with Ohio State Route 7
U.S. Route 50 (US 50) runs east–west across the southern part of the state of Ohio, passing through Cincinnati, Chillicothe, and Athens. It is mainly a two-lane road except for the easternmost and westernmost parts. Near Athens it runs concurrently with State Route 32 (SR 32), a four-lane divided highway known as Corridor D, and from Coolville to the Ohio–West Virginia border it also overlaps SR 7 before crossing into Parkersburg, West Virginia.East of Milford, US 50 becomes a two-lane highway as it travels through Hillsboro and Bainbridge before reaching the outskirts of Chillicothe. In Chillicothe, US 50 becomes Western Avenue and then Main Street before merging with U.S. Route 23 and U.S. Route 35 east of the city. State Route 104 overlaps US 50 through downtown Chillicothe.  As US 50 leaves Chillicothe it becomes a two-lane highway once again as it winds its way through McArthur and heavy forested Southern Ohio before reaching the outskirts of Athens where it becomes a four-lane highway.  It remains four-lane until reaching the Ohio River.  US 50 joins with State Route 32 near the Ohio University Bush Airport–Snyder Field in Albany, west of Athens.  US 50 intersects with U.S. Route 33 east of the city before continuing eastward toward Belpre and the Ohio River. US 50 begins to overlap SR 7 near Reedsville as it heads north along the river, and splits from SR 7 before it crosses the river on the Blennerhassett Island Bridge to Parkersburg, West Virginia.History
In 1912 the route that would become US 50 was designated Main Market Route 45. In 1923, Main Market Route 45 was decommissioned and  SR 7 replaced it from Indiana to Cincinnati. SR 27 from Cincinnati to Milford and SR 26 from Milford to Athens. US 50 replaced SR 144 from Athens to Coolville and SR 7 from Coolville to West Virginia state line. At this time the route that later became US 50 was paved between Indiana and Highland–Ross county line. In 1926 US 50 was signed on a route similar to today. The current route that US 50 between Athens and West Virginia became US 50S in 1929, with the current SR 550 becoming US 50N. US 50S and US 50N would be replaced with US 50 and US 50 Alt, in 1935.The Columbia Parkway in Cincinnati was completed in 1941 and US 50 was rerouted onto the parkway. The road west of Cincinnati became a four-lane divided highway in 1949. In 1965 the Sixth Street Expressway open and US 50 was rerouted onto the expressway. Also in that year the section of US 50 that is concurrency with SR 7 became a four-lane divided highway. US 50 was routed onto the eastern section of the Athens bypass when it open, in 1977. The western section was opened in 1979 and US 50 was route onto that year. US 50 between Athens and Coolville became a four-lane divided highway between 1997 and 1999. Between 2003 and 2007 a new bridge across the Ohio River was built.The section of the Columbia Parkway between William Howard Taft Road/Torrence Parkway and Delta Avenue has numerous abandoned staircases built into the Art Deco retaining walls (which were constructed in 1938 as part of the Works Progress Administration). The City of Cincinnati began the process of sealing up these staircases in 2008.
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