It must be noted that Los Angeles has a history of involuntary migration going back to the original 44 multiracial settlers who were likely forced to migrate to the newly founded El Pueblo de la Reyna de Los Angeles in 1781. In the 20th Century, Japanese Americans were forcibly removed and incarcerated during World War II and Mexican American families were evicted from Chavez Ravine in the 1950s to make way for affordable housing that never materialized.
For the most part, however, people have migrated to Los Angeles because of its desirability. Los Angeles began gaining importance after the independence of Mexico from Spain in 1821 and attracted people from parts of Mexico, America, and Europe. With the arrival of the Santa Fe railroad in 1885, migration was at a full gallop as real estate developers, railroad companies, and other commercial interests advertised Los Angeles as a land of sunshine and temperate climate. Wealthy Easterners and Midwesterners coming to spend winters here found themselves in love with Los Angeles, started building residences, and made the city their home. People also believed that this climate could cure chronic diseases, like consumption, and flocked to the sanitariums that cropped up in Southern California in the late 19th and early 20th century.
People continued to migrate throughout the 20th century for sunshine, temperate climate, and job opportunities in film, oil, automobile, and airplane industry, and a piece of the California dream.