Are U.S. citizens free to move to Guam, Northern Marianas, American Samoa etc.?

Can any U.S. citizen, let’s say from Nebraska or Ohio, take up residence in a U.S. territory without any restrictions? What about green card holders?

You can move to American Samoa (if you can find a job there) but it is more like moving to a different country than a different state. You need a visa and a passport as well even though it is a U.S. territory. American Samoa is an odd case in general. Its permanent residents are considered U.S. Nationals rather than U.S. Citizens. There are a number of steps you must follow to move there even as a U.S. Citizen and jobs aren’t very abundant in general.

Guam and, Northern Mariana Islands and closer islands like Puerto Rico are more like moving to a different state than a different country. You don’t need a passport, visa or other special documentation to go and stay there for the most part.

http://www.cnmiguide.com/en/moving-northern-mariana-islands

Well, there are some interesting rules:

Some background on the prickly relationship between the US and American Samoa.

Near the time my enlistment in the CG was due to expire, I became aware there was a billet for an ET2 in Pago Pago. I was a big Doonesbury fan then and I considered re-enlisting to follow the adventures of Uncle Duke.

Uncle Duke: I’m a reasonable man, MacArthur. So I know this isn’t snow.
MacArthur: Pay it no mind, Excellency - it never sticks.

One that I didn’t mention is the US Virgin Islands and it is the one that I have the most personal experience with. U.S. Citizens can just pack up and move to any of the three islands just like they can another state. I know many that have done it at one time and a few that are still there. The only minor annoyance is that that passports, while not strictly required, are still very helpful for travelling to and from the mainland U.S. unless you like carrying an official birth certificate and a government issued photo id around with you. The customs and immigration checks are also a lot more intense than travel between regular domestic airports presumably because it is so easy for people from other nearby islands to travel to the USVI by boat.

I’ve been to Guam twice. Felt like going to Florida. It’s the destination of choice for US expats in Asia who have to go visit a consulate to extend their visas.

One thing I could never get used to is the local arrangement of paying both a service charge and a tip in restaurants there.

Guam is repurposing itself as a tourist destination for high-rollers from Korea and China. In the three-year interim between my trips there, they closed down a lot of pawn shops and payday loan joints and replaced them with Gucci outlets. I hope to go back one day.