Arizona's first migrants were the ancient peoples who came from Asia across the Bering Strait more than 12,000 years ago. Hispanic settlers began arriving in the late 17th century. Anglo migration, especially from the South, became significant as the US developed westward to California, and increased at an even faster rate with the building of the railroads during the 1880s. Migration has accelerated since World War II (1939–45), and Arizona showed a net gain of 519,000 in domestic and 96,000 in international migration from 1990 to 1998. Mexico is the main source of foreign immigrants. In the 1980s, half of Arizona's total population increase was from migration; about 530,000 persons moved there during that time. By 1998, Arizona's Hispanic population numbered 963,000; those of Hispanic origin numbered 1,034,000. In 1998, 6,211 immigrants from foreign countries arrived in Arizona, of these 3,209 were from Mexico. Arizona's total population increased 27.4% between 1990 and 1998. In the period 1995–2000, 796,420 people moved into the state and 480,272 moved out, for a net gain of 316,148, 53,241 of whom were age 65 or over.