For over a hundred years, the island nation has been a US territory but Puerto Ricans do not get to vote in US elections.
The issue of the island's status is anything but straightforward. Last year's two-part referendum was criticised as confusing instead of defining the issue, and although change is growing in popularity, opinions are divided.
As Al Jazeera's Andy Gallacher reports from San Juan in the last of a three-part series, whether debt-ridden Puerto Rico should become the 51st state is still in doubt.
Source: Al Jazeera