Comendador del Rey, or Comendador for short, is the official name of the border town west of San Juan. However, almost everyone who doesn’t live there calls it Elías Piña, which is the name of the province, and you’ll have more luck using that name anywhere but in town. Comendador is best known for its twice-weekly Haitian market, when hundreds of Haitians arrive on donkeys and on foot to sell their wares.
Comendador also has a major military base and a police headquarters, and security (aimed at preventing illegal Haitian immigration) is tight. Even foreign travelers may find themselves detained and questioned if they're not carrying their passport.