Final answer:
Asians first began to migrate to the US in significant numbers with the mid-nineteenth century Chinese immigrants during the Gold Rush and the construction of the Transcontinental Railroad. Japanese immigration followed in the 1880s, and significant Korean and Vietnamese immigration occurred in the second half of the twentieth century, particularly after the Vietnam War.
Step-by-step explanation:
Asians first began to migrate to the US in significant numbers starting in the mid-nineteenth century with the Chinese as the pioneers of this movement. The Gold Rush and the construction of the Transcontinental Railroad were two main attractions that drew Chinese immigrants to the American West. These immigrants faced grueling, underpaid work but persevered despite the hardships. The influx of Chinese laborers led to discriminatory practices, such as the Chinese Exclusion Act of 1882, which limited further immigration and denied citizenship to Chinese nationals.
Following the Chinese, other Asian immigrants from countries like Japan arrived, with Japanese immigration beginning in the 1880s. Discrimination persisted, and by 1924, the Immigration Act excluded all Asians, with some exceptions, from immigrating to the U.S. or becoming naturalized citizens.
In the latter half of the twentieth century, significant numbers of Korean and Vietnamese immigrants came to the U.S. Many Vietnamese arrived as political refugees after the fall of Saigon, with the Refugee Act of 1980 providing them a means to resettle. This wave of immigration marked another significant moment when Asians began to migrate to the US in significant numbers.