In addition to the 50 states and their local governments (including cities, counties, villages and school districts), the District of Columbia and U.S. territories and possessions (American Samoa, the commonwealth of Puerto Rico, Guam, the Northern Mariana Islands, and the U.S. virgin Islands) can and do issue municipal bonds. Another important category of municipal bond issuers includes authorities and special districts, which have grown in number and variety in recent years.