State Route 578 (SR 578) is a short state highway in Clark County, Nevada. It comprises a 0.661-mile (1.064 km) portion of Washington Avenue in Las Vegas.
State Route 578 begins at Interstate 15 interchange with Washington Avenue and D Street (exits 43 and 44). From there, it follows Washington Avenue eastward, traveling under the Union Pacific railroad tracks to intersect Main Street. SR 578 passes by the southern Nevada district headquarters of the Nevada Department of Transportation as it heads eastward. The route comes to an end at the Washington Avenue intersection with Las Vegas Boulevard (former SR 604). Located at the intersection of SR 578's eastern terminus are the Grant Sawyer Building (a southern Nevada state office complex), Cashman Center and Cashman Field (home to the Las Vegas 51s baseball team), and the Old Las Vegas Mormon Fort State Historic Park (the first permanent settlement in the Las Vegas area).
SR 578 was established in the 1976 renumbering of Nevada's state highways. The route was designated on July 1, 1976.
The entire route is in Las Vegas, Clark County.
RTC Transit Routes 104, 119, 208, and 214 function on this road.