Los Angeles: 1781
Baldwin Park, formerly known as Vineland: 1860
Then the County woke up and got busy. 1874 was a very popular year with the founding of Pasadena, Santa Monica, and Alhambra, followed in 1875 by Pomona and 1878 by South Pasadena. Covina was founded in 1882, with La Puente hard on its heels in 1884.
By 1886, when Monrovia was founded, a veritable landslide of towns popped up and by the time Monrovia incorporated in 1887, the County was well on its way to the full complement of 88 cities we have today.