Historically, reasons for the of Asians to the United States were similar in some ways to those for the Atlantic migration of Europeans — to escape from poverty and civil war and to find employment opportunity and freedom. Chinese laborers were to build the transcontinental railroad in the mid-19th century and provide services in cities such as San Francisco. They were followed by the Japanese and Filipinos in the early 20th century who labored in Hawaiian , California farms, and Alaskan canneries. Of these early Asian Americans, only the Japanese were allowed to immigrate as families at the of the Japanese government. For these early generations, Asians in America were largely communities of temporary , with male to female ratios as high as 10-to-1. Asian-American children in those early years were rare. Since 1970, the of this of this population has changed tremendously. In 2002, Asian Americans were more than 4 percent of the US population. The growth of the Asian-American population since 1970 is due in great part to the of exclusionary immigration policies that existed before 1965, implementation of new statutes directly flowing from the Vietnam War, and the rise of second and US -born generations. In 1970, there were 1.5 million Asian Americans. This amounts to an eightfold to ninefold increase in little more than 30 years.