When Spanish occupation of California began in 1769, an exploratory expedition of more than 60 persons led by Gaspar de Portolá moved north through the area now known as Los Angeles. They camped by a river where fertile soil and availability of water for irrigation impressed members of the party. Father Juan Crespi, who accompanied the group, saw the location as having all the requirements for a large settlement. He named the river El Río de Nuestra Señora la Reina de Los Angeles de Porciúncula, which means "The River of Our Lady the Queen of the Angels of Porciúncula."
Twelve years after Portolá's trek, which began in San Diego and ended in Monterey, a company of settlers called "Los Pobladores" were recruited in the states of Sonora and Sinaloa in Mexico. Their mission, under authority of Governor Felipe de Neve, was to establish pueblos in the name of the King of Spain.
On September 4, 1781, the Pobladores, a group of 12 families - 46 men, women, and children - established a community in the area discovered by Portolá, and named it El Pueblo de Nuestra Señora la Reina de Los Angeles de Porciúncula, after the nearby river. Over time, the city became known as the Ciudad de Los Angeles, "City of Angels", and was destined to become the great city of the West now known as "Los Angeles."
California was ruled by Spain until 1822 when Mexico assumed jurisdiction. After a two year period of hostilities with Mexico beginning in 1846, the area came under U.S. control. In 1848 the Treaty of Guadalupe made California a United States territory.
The County of Los Angeles was established on February 18, 1850 as one of the 27 original counties. It derived its name from that of the City of Los Angeles (the designated "seat" of County government) which had already become a large community. On April 1, 1850 the people of Los Angeles County asserted their newly won right of self-government and elected a three man Court of Sessions as their first governing body. A total of 377 votes were cast in this election. In 1852 the Legislature dissolved the Court of Sessions and created the five-member Board of Supervisors. In 1913 the citizens of Los Angeles County approved a charter recommended by a board of freeholders which gave the County greater freedom to govern itself within the framework of state law.