There are 78 municipalities in Puerto Rico.
Names from CIA World Factbook (http://www.cia.gov/cia/publications/factbook/geos/rq)
... 3.52. In the town the population is spread out with 26.0% under the age of 18, 9.4% from 18 to 24, 34.6% from 25 to 44, 19.4% from 45 to 64, and 10.6% who are 65 years of ...