The only people who made it an issue in 1964, and it was barely an issue, was the kooky left.
It’s actually not a “slam dunk.” Puerto Rico also is a territorial possession, but the presidential eligibility issue for Puerto Ricans is not resolved.
http://www.puertorico-herald.org/issues/2003/vol7n38/Poll0738-en.html
This is why Justice Thomas and Rep. Serrano had a recent joking exchange about the matter.
It’s actually not a “slam dunk.” Puerto Rico also is a territorial possession But it's status is different than Hawaii or Alaska's were when they were territories.
They were " annexed as a part of the territory of the United States and subject to the sovereign dominion thereof." They like the other states, and the territories they were formed from were "incorporated territories". Puerto Rico was at first an "unincorporated territory", and has been a "Estado Libre Asociado" (Free Associated State) or commonwealth since 1952. But it's still not an "incorporated territory".
At least one VP was born in a territory before it became a state. Charles Curtis of Kansas, born on January 25, 1860, over a year before Kansas became a state on January 29, 1861, was Herbert Hoover's Vice President. He was also "native American", being 1/8th each of Kansa Indian, of Osage Indian, of Potawatomi Indian, and 1/8th French. His father was "an American" of English ancestry.
Actually Puerto Rico is a “commonwealth” not a “territory”, its an interesting Constitutional question as to whether that makes a difference.
If Puerto Rico did vote for statehood (so far they keep selecting commonwealth status!) would they then be a “territory” then a “state” or would then go right to “state” status.
There is a very different history for Puerto Rico vs say Ohio, or even Hawaii so if Puerto Rico eventually chooses statehood it will be interesting!