Washington Parish is a parish located in the U.S. state of Louisiana. As of the 2010 census, the population was 47,168. Its parish seat is Franklinton. The parish was founded in 1819.Washington Parish comprises the Bogalusa, LA Micropolitan Statistical Area, which is included in the New Orleans-Metairie-Hammond, LA-MS Combined Statistical Area.HistoryWashington Parish was formed in 1819 by splitting off from St. Tammany Parish. Franklinton became the parish seat on February 10, 1821.Washington Parish is the most northeasterly of what are called the Florida Parishes. Great Britain took over control of French territory east of the Mississippi River in 1763 after defeating France in the Seven Years' War. But France had ceded some territory to Spain. This area was under contention, and English and American settlers tried to set up an independent state in 1810. The United States annexed it, later settling with Spain in a treaty. Through much of this period, the French influence remained strong in the region, especially in its former colonial cities.
