The province is bordered by Ilocos Sur to the north, Benguet to the east, Pangasinan to the south and to the west by the shores of the South China Sea (West Philippine Sea).
La Unión, "The Union" in Spanish, was formed in 1850 when the Spanish colonial government of Governor-General Antonio Maria Blanco merged the three southern towns of Ilocos Sur province, the nine northern towns of Pangasinan, and the western towns of Benguet to the east (Eastern Pais del Igorotes in the Cordilleras). Pangasinenses were the majority in the new province because most towns had been in the province of Pangasinan.
On October 29, 1849, Governor General Claveria issued a promovido to fuse the Pangasinan-Ilocos-Cordillera areas into La Union. On March 2, 1850, Governor General Antonio Maria Blanco signed the Superior Decreto of La Union (34th province from Cebu-1565), with Captain Toribio Ruiz de la Escalera as the first Gobernador Military y Politico. Isabella II of Spain decreed the province's creation on April 18, 1854. In 1661, Andres Malong (Pangasinan) failed to recover La Union from the Spaniards after the Battle of Agoo. In 1896, the people of La Union began a revolt against the Spaniards, who had called La Union "Una Provincia Modelo" ("A Model Province"), led by Manuel Tinio Y Bondoc under Emilio Aguinaldo. The Americans collaborated with the Filipinos to end the Spanish.
Dr. Lucino Almeida became the Presidente Provincial of the American regime, followed by the election of La Union’s first Civil Governor in 1901, Don Joaquin Joaquino Ortega.
On January 4, 1945, La Union was liberated by the Battle of San Fernando and Bacsil Ridge.
La Union covers a total area of 1,497.70 square kilometres (578.27 sq mi) occupying the central‑southern section of the Ilocos Region in Luzon. The province is bordered by Ilocos Sur to the north, Benguet to the east, Pangasinan to the south, and to the west by the South China Sea.
La Union is 273 kilometres (170 mi) north of Metro Manila and 57 kilometres (35 mi) northwest of Baguio City. The land area of the province is 149,770 hectares (370,100 acres).
Like most of the Ilocos Region, the province is squeezed in by the Cordillera mountain range to the east and the South China Sea to the west. Yet, unlike other portions of Luzon and the Philippines' two other island groupings, the Visayas and Mindanao, La Union experiences a rather arid and prolonged dry season with little precipitation to be expected between the months of November and May.
La Union comprises 19 municipalities and 1 component city, all of which are organized into two legislative districts.
La Union has a total of 576 barangays comprising its 19 municipalities and 1 city.
The most populous barangay in the province is Sevilla in the City of San Fernando with a population of 10,612 in the 2010 census. If cities are excluded, Central East (Poblacion) in the municipality of Bauang has the highest number of inhabitants, at 4,249. Caggao in Bangar has the lowest with only 170.
The population of La Union in the 2015 census was 786,653 people, with a density of 530 inhabitants per square kilometre or 1,400 inhabitants per square mile.
The province is predominantly Ilocano (over 90% based on recent census data) and Roman Catholic. communities of Pangasinans thrive mostly in the southwestern portion of the province while Cordillerans live in the Cordillera foothills. In September 2012, the province of La Union passed an ordinance recognizing Ilocano (Iloko) as an official provincial language alongside Filipino and English, as national and official languages of the Philippines, respectively.
La Union is known for its softbroom industry. The economy is diversified with service, manufacturing, and agricultural industries spread throughout the province. The Port of San Fernando operates as an increasingly active shipping point, and the former American airbase Wallace Air Station, having been converted into a business and industrial area, helps to facilitate such commercial activity.
The major products of the province include: hand-woven blankets (Inabel), softbrooms, baskets, pottery, rice wine (tapuey), sugarcane wine (basi), sugarcane vinegar, wood craft, bamboo craft, native rice cakes, antique-finish furniture, dried fish, coconuts, sea urchins, malunggay, and pebble stones.
La Union has 333 public elementary schools, 56 private elementary schools, 79 public high schools, 51 private secondary schools, 20 Colleges and 5 State Universities.
Just as the national government, La Union provincial government is divided into three branches: executive, legislative and judiciary. The judicial branch is administered solely by the Supreme Court of the Philippines. The LGUs have control of the executive and legislative branch.
The executive branch is composed of the governor for the provinces, mayor for the cities and municipalities, and the barangay captain for the barangays.
The legislative branch is composed of the Sangguniang Panlalawigan (provincial assembly) for the provinces, Sangguniang Panlungsod (city assembly) for the cities, Sangguniang Bayan (town assembly) for the municipalities, Sangguniang Barangay (barangay council), and the Sangguniang Kabataan for the youth sector.
The seat of Government is vested upon the Mayor and other elected officers who hold office at the City Hall of San Fernando. The Sanguniang Bayan is the center of legislation, stationed in the Speaker Pro-Tempore Francisco I. Ortega Building, the Legislative Building at the back of the Capitol.
La Union is governed by Manuel C. Ortega, the Chief Executive, his Vice Governor, Aureo Augusto Nisce and 13 Board Members.
Dr. Lucino Almeida became the Presidente Provincial of the American regime, followed by the election of La Union’s first Civil Governor in 1901, Don Joaquin Joaquino Ortega, Grandfather of Governor Manuel C. Ortega. 9 Governors succeeded Don Joaquin before World War II: Joaquin Luna, 1904-1907, Sixto Zandueta, 1908-1919, Pio Ancheta 1919-1922, 1931, Thomas De Guzman, 1922-1923, 1928-1931, Juan Lucero, 1923-1929, Mauro Ortiz, 1931-1934, Juan Rivera, 1934-1937, Francisco Nisce, 1937-1940 and Bernardo Gapuz, 1940. Gov. Bernardo Gapuz (1940), Gov. Jorge Camacho (1941-1942) and Gov. Bonifacio Tadiar (1942-1944) thereafter succeeded these 9.
Agaton Yaranon, 1946-1947 was succeeded by Governors: Doroteo Aguila, 1948-1951, Juan Carbonell, 1952-1955, Bernardo Gapuz, 1956-1959, Eulogio De Guzman, 1960-1967, Juvenal Guerrero, 1968-1977, Tomas Asprer, 1977-1986, Robert V. Dulay, 1986-1987, Joaquin Ortega, 1988-1992, Justo O. Orros, 1992-2001, Victor F. Ortega, 2001-2007, Manuel C. Ortega, 2007–2016, and Francisco Emmanuel R. Ortega, III, 2016-Present.
The Supreme Court of the Philippines recognizes La Union (inter alia) regional trial courts and metropolitan or municipal trial courts within the province and towns, that have an over-all jurisdiction in the populace of the province and towns, respectively.
Batas Pambansa Blg. 129, "The Judiciary Reorganization Act of 1980", as amended, created Regional, Metropolitan, Municipal Trial and Circuit Courts. The Third Judicial Region includes RTCs in La Union xxx Sec. 14. Regional Trial Courts. (a) Fifty-seven Regional Trial Judges shall be commissioned for the First Judicial Region. Nine branches (Branches XXVI to XXXIV) for the province of La Union, Branches XXVI to XXX with seats at San Fernando, Branches XXXI and XXXII at Agoo, Branch XXXIII at Bauang, and Branch XXXIV at Balaoan;
The law also created Metropolitan Trial Courts in each metropolitan area established by law, a Municipal Trial Court in each of the other cities or municipalities, and a Municipal Circuit Trial Court in each circuit comprising such cities and/or municipalities as are grouped together pursuant to law: three branches for Cabanatuan City; in every city which does not form part of a metropolitan area, there is also a Municipal Trial Court with one branch, except as provided: Two branches for San Fernando, La Union;
The courts of law are stationed in Halls of Justices of the Province and towns. In La Union, the Regional Trial Court is stationed at the Bulwagan ng Katarungan or Halls of Justice in San Fernando, La Union and other Regional Trial Courts in Bauang and Agoo, La Union.