Wikipedia:WikiProject U.S. Roads/Pennsylvania/Selected article/November 2012

Pennsylvania Route 378 (designated by the Pennsylvania Department of Transportation as SR 378) is a north-to-south road in Lehigh and Northampton counties. Its northern terminus is at U.S. Route 22 in Bethlehem and the portion north of the Lehigh River is a freeway. The highway was once Interstate 378 but when Interstate 78 was rerouted from U.S. Route 22 to south of the city, the spur became disjointed from its parent. I-378 was downgraded to state route status. Surprisingly, the state did not remove the exit tabs for the freeway, making PA Route 378 one of only a few state freeways with exit numbers (another one is PA 309 in Wilkes-Barre.) The exit numbers also go in the wrong direction: Exit 3 is south of Exit 1, most likely due to the freeway being built when Pennsylvania still practiced sequential exit numbering.

It narrows to a city street on Bethlehem's South Side, crosses South Mountain to Lower Saucon Township, then proceeds to its southern terminus at PA 309 in Center Valley. PA 378 was originally known as Pennsylvania Route 191 south of the river. Today, PA Route 378 is the only highway from US 22 to Center City, and a quick route for visitors traveling to the Sands Casino Resort on the city's South Side. In 2009, the portion north of the Lehigh River was named the Fred B. Rooney Highway. Construction from West Broad Street to U.S Route 22 (Lehigh Valley Thruway) began in 1966 and finished in 1968. At that time, the segment received the Interstate 378 designation. It was changed to PA 378 in 1971 after I-378 was deleted. In 1974, the designation replaced Pennsylvania Route 191 from Center Valley to Third Street in Bethlehem.