And a local referendum is not how you become a state, Congressional approval is. A local referendum might help make that happen, but it's in no way the required legal mechanism or binding in any way.

Article IV (in part):

New States may be admitted by the Congress into this Union;

...

The Congress shall have Power to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States;

I lived in Puerto Rico and know lots of people in government there. The lack of action is entirely down to the Puerto Rican government and has nothing to do with the USA federal government. Turnout in the referendums was too low for it to be considered valid, at least according to one of their major political parties.

Too many rich people and politicians benefit from the lack of oversight and low taxes plus the corruption that results for them to allow statehood. If Puerto Ricans are serious about wanting statehood they can stop voting for these corrupt clowns anytime and vote in people that will complete the process of obtaining statehood.

> Turnout in the referendums was too low for it to be considered valid, at least according to one of their major political parties.

Turnout in the 2012 referendum was 78%.

And turnout in the 2017 referendum was 23%.

But on 2012: of 1,878,969 voters, 515,115 (27% of turnout) left the choice between statehood, independence, or free association blank at the behest of the PPD, who’s governor elect immediately asked President Obama to ignore the results due to ambiguity, while the outgoing PNP governor asked President Obama to begin the legislation process.

It’s not even remotely as simplistic as you’re implying by dropping a 78% figure and flitting away without any further context, have the decency to at least read the links you’ve posted.