Anyway, you say a sovereign nation has a right and an obligation to control its borders. So would you say the U.S. ignored this obligation for most of its history?
Seems to me immigration law now is more liberal than it ever has been.
American immigration history can be viewed in four epochs: the colonial period, the mid-nineteenth century, the turn of the twentieth, and post-1965. Each epoch brought distinct national groups - and races and ethnicities - to the United States. During the 17th century, approximately 175,000 Englishmen migrated to Colonial America.[11] Over half of all European immigrants to Colonial America during the 17th and 18th centuries arrived as indentured servants.[12] The mid-nineteenth century saw mainly an influx from northern Europe; the early twentieth-century mainly from Southern and Eastern Europe; post-1965 mostly from Latin America and Asia.
Historians estimate that less than 1 million immigrants ? perhaps as few as 400,000 ? crossed the Atlantic during the 17th and 18th centuries.[13] In the early years of the United States, immigration was fewer than 8,000 people a year,[14] including French refugees from the slave revolt in Haiti. After 1820, immigration gradually increased. From 1836 to 1914, over 30 million Europeans migrated to the United States.[15] The death rate on these transatlantic voyages was high; one in seven travellers died.[16]
In 1875, the nation passed its first immigration law.[17]
The peak year of European immigration was in 1907 when 1,285,349 persons entered the country. By 1910, 13.5 million immigrants were living in the United States. In 1921, the Congress passed the Emergency Quota Act, followed by the Immigration Act of 1924. The 1924 Act was aimed at lowering the overall inflow and making it proportionate to the ethnicities of the people already in the U.S.[18]
Immigration patterns of the 1930s were dominated by the Great Depression, which hit the U.S. hard and lasted over ten years there. In the last prosperous year (1929), there were 279,678 immigrants recorded, but in 1933 only 23,068 came to the U.S. In the early 1930s, more people emigrated from the United States than immigrated to it. The U.S. government sponsored a Mexican Repatriation program which was intended to encourage people to voluntarily move to Mexico, but thousands were deported against their will. Altogether about 400,000 Mexicans were repatriated.[19]
The Immigration and Nationality Act Amendments of 1965 (the Hart-Cellar Act) abolished the system of national-origin quotas. By equalizing immigration policies, the act resulted in new immigration from non-European nations which changed the ethnic make-up of the United States.[20] While European-born immigrants accounted for nearly 60% of the total foreign-born population in 1970, they accounted for only 15% in 2000. Immigration doubled between 1965 and 1970, and doubled again between 1970 and 1990.[21] In 1990, President Bush signed the Immigration Act of 1990,[22] which increased legal immigration to the United States by 40%.[23] Nearly 8 million immigrants came to the United States from 2000 to 2005 ? more than in any other five-year period in the nation's history.[24] Almost half entered illegally.[25] Since 1986, Congress has passed seven amnesties for illegal immigrants.[26]
http://en.wikipedia.org/wiki/Immigration_to_the_United_States#History