Las Vegas' birthday is celebrated on May 15, as on that date in1905, 110 acres of land situated between Stewart Avenue on the north, Garces Avenue to the south, Main Street to the west, and Fifth Street (Las Vegas Boulevard) to the east, were auctioned off by the railroad company. On June 1, 1905, Las Vegas became a city with it's first mayor. The completion of the San Pedro, Los Angeles & Salt Lake Railroad, linking Southern California with Salt Lake City, established Las Vegas as a railroad town. The availability of water made Las Vegas an ideal refueling point and rest stop. Along with the railroad townsite there was a second townsite that J. T. McWilliams (now Historic West Las Vegas) west of the railroad tracks.

The Historic Westside School was built on what is now Washington Avenue and D Street. The building was the first grammar school in West Las Vegas and is the oldest remaining schoolhouse in Las Vegas. The school is listed on the city of Las Vegas Historic Property Register, and the Nevada and National Register of Historic Places.

The Las Vegas Army Air Field (now Nellis Air Force Base) was built in the northeast. The western-style El Rancho Vegas hotel‐casino, became the first themed resort on what would become The Strip. This was followed by the Last Frontier (1942), Flamingo (1946) and Thunderbird (1948) hotels and casinos. On Fremont Street the El Cortez hotel‐casino opened.

Tennessee Congressman Carey Estes Kefauver held hearings into the mob at the U.S. Post Office and Courthouse in downtown Las Vegas. This historic building at 300 Stewart Ave. is still in use today and is the home of The Mob Museum. Visitors can learn about the history of organized crime and the federal agents who fought against it in Las Vegas.

Starting in the mid 1980s, a period of unprecedented growth began. Annual population increases averaging nearly seven percent caused the city's population to almost double between 1985 and 1995, increasing 97.6 percent from 186,380 to 368,360.

The three-block area known as the Fremont East Entertainment District opened. As part of its downtown revitalization efforts, the city’s Redevelopment Agency contributed funds to this renovation in an effort to attract additional non-gaming nightclubs, cocktail lounges and entertainment hot spots to the area.