Puerto Rico Municipio Population Density

As expected, the areas with highest or above average Density are the San Juan Metro, Caguas Ponce (to a lesser degree) and the Gurabo-Humacao Corridor. 

Unexpectedly, Aguadilla has a ~1,500 people per sqr Mile Population density, as it the 12th most populous municipio, falling behind the less dense Mayagüez, Vega Alta and Vega Baja

Overall Puerto Rico is the 4th Most population dense locality in the United States, falling behind Washington DC, New Jersey, and Rhode Island