However, the 1906 San Francisco earthquake and fire destroyed immigration records, resulting in the immigration of paper sons and daughters: many Chinese American residents of San Francisco claimed to have been born in the city to gain citizenship under the Fourteenth Amendment; their offspring would then be citizens as well. Numerous emigrants from China purchased papers attesting they had an American citizen as a parent. At the same time, Chinatown was rebuilt but remained geographically limited by restrictive racial covenants that prevented Chinese residents from purchasing or renting outside its boundaries; the transformation from what used to be a largely bachelor society of Chinese laborers through the immigration of women and the growth of families, combined with the hard borders of Chinatown, meant the population and density grew steadily through the early 20th century.