alternate route or from the southbound alternate route to eastbound Patapsco Avenue; those movements are made via Washington Boulevard. US 1 Alt. heads north as a six-lane divided highway through a seven-ramp partial cloverleaf interchange with I-95. The highway reduces to a four-lane undivided highway and passes by Seton Keough High School, the former Cardinal Gibbons School, and St. Agnes Hospital before reaching its northern terminus at US 1 (Wilkens Avenue). Caton Avenue continues north through western Baltimore toward MD 144 and US 40. All of US 1 Alt. is a part of the National Highway System as a principal arterial. History Washington Boulevard was first laid out as the highway southwest from Baltimore in 1741 and was improved by the Baltimore and Washington Turnpike Company starting in 1812. After the state condemned the turnpike in 1865, maintenance of the highway became the responsibility of the counties. In 1906, the state took over maintenance as the road as part of its construction of State Road No. 1. The highway from west of the Pennsylvania Railroad (now Amtrak's Northeast Corridor) to the city limits of Baltimore at Gwynns Falls was reconstructed as a concrete road by 1915. The work included a bridge across the Pennsylvania Railroad at Winans. Washington Boulevard was widened to with a pair of concrete shoulders and resurfaced with sheet asphalt in 1918, part of a project to expand the entire highway from Washington DC to Baltimore to . The highway, which was marked as US 1 in 1926, was widened to with the addition of a pair of concrete shoulders, and resurfaced with sheet asphalt in the late 1920s. Caton Avenue was paved as a concrete road from Washington Boulevard to Wilkens Avenue starting in 1930. Caton Avenue was widened and repaved, along with Wilkens Avenue east from Caton Avenue, in 1936 as part of plans to create through-traffic streets through Baltimore for US 1 and US 40 traffic. That same year, Washington Boulevard's modern bridge across the Pennsylvania Railroad was completed. US 1 originally followed Washington Boulevard and Monroe Street in southwest Baltimore, but the highway was rerouted along Caton Avenue and Wilkens Avenue by 1939. After US 1 was moved to its present course along Wilkens Avenue and Southwestern Boulevard in 1949, the old route of the U.S. Route along Washington Boulevard and Caton Avenue became US 1 Alt. Further expansion of US 1 Alt.