In 1848, the first Chinese immigrants, two men and one woman, arrived in San Francisco on the American sailing vessel, Eagle. The long history of San Francisco’s Chinatown has been clouded with racism, hatred, and repression. From the Gold Rush through the 1870s, a large migration of mostly single male laborers came to San Francisco and the American West, as well as to Canada and Peru. With the Chinese Exclusion Act of 1882, the nation's first racially restrictive immigration measure, the Chinese American population fell from 26,000 in 1881 to 11,000 in 1920. Between 1852 and 1882, many prodominantly male Chinese laborers and a few merchants and labor brokers came to San Francisco. Floods in China propelled a virtual diaspora of Cantonese-dialect-speaking people all around the Pacific Basin. It has been estimated that 2.5 million people emigrated from China between 1840 and 1900. Of 153 pieces of property in Chinatown in 1873, only 10 were Chinese owned. All the rest were leased from Anglo-Americans, Franco-Americans, Italian Americans, and German Americans. In 1882, Chinatown's habitually suspicious key associations formed an umbrella association, uniting the most important of the district associations in what became known as the Chinese Six Companies, officially called the Consolidated Chinese Benevolent Association. The association, incorporated in the State of California in 1901, became the cockpit of personal and group political, economic, and social contention. In 1904, of 316 parcels, Chinese-Americans owned only 25. As Chinese immigration dwindled, and as individual assimilation took place, parochial clan and regional attachments weakened. While the Chinese were, practically speaking, segregated within Chinatown until the late 1940s, some assimilation nonetheless took place. In 1943, during World War II when the United States allied with China against Japan, the Chinese Exclusion Act was repealed by Congress, but a small quota of 105 Chinese a year kept migration minimal. The post-World War II era saw the economic and social advance of Chinese Americans. The nullification of California's antimiscegnation law in 1948, and the striking down of racially restrictive covenants in the sale of California real estate in the same year, emancipated Chinese Americans and other Asian Americans. When the Nationalist government retreated to Taiwan in 1949, an influx of Mandarin-speaking professionals and wealthy merchants fled Red China to San Francisco. In 1965, the Civil Rights Act was passed and the United States began to break through the psychological and legal barriers of its historic racial antipathies and to put a positive spin on the reality of its multiracial society. In the same year, immigration quotas were reconfigured to reflect a multiracial reality and to permit more Asian immigration. From 105 a year, quotas for Chinese grew to 20,000 per year by 1970. By that time, 56 percent of Chinese Americans were in white-collar occupations. Since the late 1970s, more and more Chinese from Vietnam, along with other Southeast Asian peoples, have arrived in San Francisco. By 1970, 52 percent of all San Franciscans of Chinese ancestry were foreign born. The new immigration laws favor migrants with skills and/or large amounts of money. Ramshackle old Chinatown was completely wiped out by the fire of 1906. When the district was rebuilt by non-Chinese absentee landowners, between 1906 and about 1929, a newer, cleaner if still extraordinarily dense, early-20th-century city of remarkable consistency emerged. Those new buildings conformed to better municipal building laws that required brick or concrete construction in the "congested district." The resulting Edwardian buildings are the stuff of today's Chinatown. In the early 1970s new Chinese-style Chinese-American architects contributed designs. Today, Chinatown is one of the densest neighborhoods in the nation with some 160 people per acre: second only to New York City's Chinatown. Seventy-five percent of its residents are foreign-born; the comparable citywide proportion is 28 percent. The median household income there is about $10,000, one-third the median income of the city as a whole.