1572 – Juan Salcedo lands in Agoo to start colonization of Ilocos; fights Ilocanos in Battle of Purao (Balaoan)

1849 – Gov. Gen. Narciso Claveria signs Promovido to unite parts of Pangasinan, Ilocos and Cordillera into a new province to be called La Union

1850 – Gov. Gen. Antonio Blanco signs Superior Decreto that founded La Union on March 2 with Santo Tomas, Agoo, Aringay, Caba, Bauang, Naguilian, San Fernando, San Juan, Bacnotan, Balaoan, Bangar & Luna

1854 – Queen Isabella II of Spain issues Royal Decree confirming Blanco’s Superior Decreto on April 8

1860 – Tobacco brings dramatic progress and development to La Union; Tobacco Monopoly established

1864 – Rosario becomes a municipality

1885 – Tubao becomes a municipality

1896 – Spanish Revolution starts, native priests tortured; Balaoan elite now known as Siete Martires, executed; and Masons prosecuted

1898 – Much –hated Friar Mariano Garcia of Santo Tomas shot dead on May 22, igniting revolution in the province. Gen. Manuel Tinio liberates La Union and appointed “de facto governor” who was later replaced by Dr. Lucino Almeida. Locals join Filipino-American War

1901 - Don Joaquin Joaquino Ortega is elected as La Union's first Civil Governor

1940 - La Union suffers and fights under Japanese Occupation

1945 - Filipino and American soldiers capture Baroro Bridge on January 4, emerging victorious at the Battle of San Fernando and Bacsil Ridge, ensuring liberation of La Union

1947 - San Gabriel, Pugo and Sudipen turn into municipalities

1949 - Municipality of Santol created

1962 - Burgos becomes a Municipality

1963 - Bagulin turns into a Municipality

1988 - Then Mayor now Gov. Manuel C. Ortega closes violent chapter of San Fernando, catapulting it to progress and development

1998 - San Fernando becomes a city through the initiative of La Union 1st District Cong. Victor F. Ortega and then Mayor now Gov. Manuel C. Ortega

2010 - Bauang Private Power Corporation management is formally turned-over to PGLU after a Supreme Court landmark ruling for non-payment of realty tax, a precendent among LGUs of the Philippines

2011 - PGLU wins much-coveted Pamana ng Lahi

2012 - PGLU is 2nd Best Performing Province in the Philippines