Section 4(c)
An immigrant who was born in the Dominion of Canada, Newfoundland, the Republic of Mexico, the Republic of Cuba, the Republic of Haiti, the Dominican Republic, the Canal Zone, or an independent country of Central or South America, and his wife, and his unmarried children under 18 years of age, if accompanying or following to join him;

http://www.usconstitution.com/immigrationactof1924.htm

In other words there was no limit on the # of immigrants from the Americas. The immigrants had to follow the other rules outlined in the 1907 and 1924 regulation with respect to health and mental status.

The 1965 reg actually stripped this language.

Jenna has already responded to my earlier post about immigration. In her response, she makes two arguments for why we should have border laws and immigration laws. The first is that American citizenship is valuable — too valuable to simply be han…

Steven Taylor reviews the US immigration laws that lead up to the critical Immigration and Naturalization Act of 1965. Personally, I’ve always thought the 1965 Act was one of the most beneficial pieces of legislation in our nation’s history. Why?

So yes, immigration was restricted by nationality. But in the current immigration debate, we’re not really talking generically about immigration from wherever. We’re talking about Mexicans (and other Latin Americans to a certain extent). Gonzales’s grandparents were Mexican immigrants and, prior to 1965, there were no legal restrictions on immigration from Mexico.

This also puts the lie to the whole national security argument. Of course this is just about Mexican immigration and has nothing to do with terrorists sneaking across the border. If not, why are we also not discussing controlling our northern border, which is just as, if not more, permeable than the southern border?