The Aguadilla-Isabela-San Sebastián Metropolitan Statistical Area is a United States Census Bureau

United States Census Bureau

The United States Census Bureau is the government agency that is responsible for the United States Census. It also gathers other national demographic and economic data...

 defined Metropolitan Statistical Area (MSA) in northwestern Puerto Rico

Puerto Rico

Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

. A July 1, 2009 Census Bureau estimate placed the population at 342,495, a 9.56% increase over the 2000 census

United States Census, 2000

The Twenty-second United States Census, known as Census 2000 and conducted by the Census Bureau, determined the resident population of the United States on April 1, 2000, to be 281,421,906, an increase of 13.2% over the 248,709,873 persons enumerated during the 1990 Census...

 figure of 312,602.

Aguadilla-Isabela-San Sebastián is the second largest metropolitan area (by population) in Puerto Rico after San Juan–Caguas–Guaynabo

San Juan-Caguas-Guaynabo metropolitan area

The San Juan-Caguas-Guaynabo Metropolitan Statistical Area is a United States Census Bureau defined Metropolitan Statistical Area in northeastern Puerto Rico...

 and is the fastest growing MSA in the Commonwealth.

Municipalities

A total of eight municipalities are included as part of the Aguadilla-Isabela-San Sebastián Metropolitan Statistical Area. They are:

• Aguada
  Aguada, Puerto Rico
  Aguada is a municipality of Puerto Rico, located in the western coastal valley region bordering the Atlantic Ocean, west of Rincón, Aguadilla and Moca; and north of Anasco. It is part of the Aguadilla-Isabela-San Sebastián Metropolitan Statistical Area...
  
  
• Aguadilla
  Aguadilla, Puerto Rico
  Aguadilla , founded in 1775 by Luis de Córdova, is a city located in the northwestern tip of Puerto Rico bordered by the Atlantic Ocean to the north and west, north of Aguada, and Moca and west of Isabela. Aguadilla is spread over 15 wards and Aguadilla Pueblo...
  
  --Principal City
• Añasco
  Añasco, Puerto Rico
  Añasco , named after one of its settlers, Don Luis de Añasco, is a municipality of Puerto Rico located on the west coast of the island bordering the Mona Passage to the west, north of Mayagüez, and Las Marias; south of Rincón, Aguada, and Moca and west of San Sebastián and Las Marias...
  
  
• Isabela
  Isabela, Puerto Rico
  Isabela is a municipality of Puerto Rico located in the north-western region of the island, north of San Sebastián; west of Quebradillas; and east of Aguadilla and Moca. Isabela is spread over 13 wards and Isabela Pueblo...
  
  --Principal City
• Lares
  Lares, Puerto Rico
  Lares is a small mountain municipality of Puerto Rico's central-western area located north of Maricao and Yauco; south of Camuy, east of San Sebastián and Las Marias; and west of Hatillo, Utuado and Adjuntas. Lares is spread over 10 wards and Lares Pueblo...
  
  
• Moca
  Moca, Puerto Rico
  Moca is a municipality of Puerto Rico located in the north-western region of the island, north of Añasco; southeast of Aguadilla; east of Aguada; and west of Isabela and San Sebastián. Moca is spread over 12 wards and Moca Pueblo...
  
  
• Rincón
  Rincón, Puerto Rico
  Rincón is a municipality of Puerto Rico founded in 1771 by Don Luis de Añasco . It is located in the Western Coastal Valley, west of Añasco and Aguada. Rincón is spread over 8 wards and Rincón Pueblo...
  
  
• San Sebastián
  San Sebastián, Puerto Rico
  San Sebastián is a municipality of Puerto Rico located northwest of the island south of Isabela and Quebradillas; north of Las Marías; east of Moca and Añasco; and west of Lares. San Sebastián is spread over twenty-four wards and San Sebastián Pueblo...
  
  --Principal City