A commenter on my previous post wrote that "Having open borders renders the entire concept of a country meaningless." ….
1. Ellis Island was only established as a federal immigration point—the first such—in 1890.
2. The first federal restrictions on immigration were passed in 1875; they excluded criminals, prostitutes, and Chinese contract laborers. Congress passed the first general law restricting immigration in 1882, banning immigration from China. In 1917 the restriction was extended to immigrants from other Asian Pacific countries. Numerical immigration quotas only came in in 1921, but did not apply to immigrants from Latin America until 1965.
3. While it is hard to be certain, it does not sound as though there was any effective mechanism for enforcing restrictions in the early period. That was obviously true for immigration across land borders, and I do not think there was any enforcement mechanism covering all ports that would have prevented someone from simply walking off a ship and blending into the local population—easy to do anywhere with a significant group of the immigrant's ethnicity…..
My conclusion is that if the concept of a country is meaningless without at least nominal restrictions on immigration, the U.S. only came into existence about 1875. If the restrictions have to be real—i.e. effectively enforced—the U.S., if it exists at all, has been a country for only a few decades….
It used to be, in general, a passportless world. It is always good to return to Reason's classic 2006 cover package story "Immigration Now, Immigration Tomorrow, Immigration Forever."