On April 4, 1850, Los Angeles was incorporated as a U.S. city (official California statute). What was known as Pueblo de Los Angeles had become the City of Los Angeles. Should note that Los Angeles became a U.S. city before California became a U.S. state.

In 1950, Los Angeles Mayor Bowron (dressed as a gentleman of the early days) led the festivities celebrating 100 years as a U.S. city. And while April 4, 1850 can be considered one birthday, Los Angeles also celebrates its founding on September 4, 1781. Photo comes from the Herald Examiner Collection of the Los Angeles Public Library.