St. Tammany was originally inhabited by numerous Indian peoples, including the Colapissas, Bayou Goulas, Chickasaw, Biloxi, Choctaw and Pensacola nations. In 1699, Pierre Le Moyne d’Iberville, a French explorer, was the first European to visit the area of present-day St. Tammany Parish. While exploring lakes Pontchartrain and Maurepas, Iberville wrote in his journal, “The place where I am is one of the prettiest I have seen, fine level ground bare of canes. The land north of the lakes is a country of pine trees mixed with hard woods. The soil is sandy and many tracks of buffalo and deer can be seen.”
After the French were defeated in the French and Indian War, St. Tammany (like the surrounding regions of the Florida Parishes) became part of English West Florida. Then, after Britain was defeated in the American Revolutionary War, West Florida was governed by the British and the Spanish. During the West Florida period, St. Tammany, like the rest of West Florida, attracted British loyalists who wanted to escape persecution in the 13 colonies. The West Florida period ended with the West Florida Revolt, which preceded West Florida’s annexation by the United States.
In 1810, President James Madison claimed West Florida as part of Louisiana and sent William C. C. Claiborne to claim the territory. Claiborne established the boundaries of the Florida Parishes. He created St. Tammany Parish and named it after the Delaware Indian Chief Tamanend (c.1628-1698), who made peace with William Penn and was generally renowned for his goodness. Among the nine Louisiana parishes (counties) named for “saints”, St. Tammany is the only one whose eponym is not a saint as recognized by the Roman Catholic Church, the ecclesiastical parishes of which formed the basis for civil parishes prior to statehood. In fact, Tamanend is not known to have been a Christian, and was certainly not a Roman Catholic. However, he became popularly revered as an “American patron saint” in the post-Revolutionary period (long after his death).
In the early 1830s, there were only two towns in St. Tammany: Covington, a retreat with summer homes and hotels; and Madisonville, a shipbuilding and sawmill town. The area south of Covington to Lake Pontchartrain’s northern shore and extending eastwards to the Pearl River border with the state of Mississippi was known as the Covington Lowlands. This region included the present-day towns of Mandeville, Abita Springs, Lacombe, Slidell, and Pearl River. Mandeville was founded in 1834 and was developed as a health resort for wealthy New Orleanians, because it was believed that ozone was both salutary and naturally emitted by the numerous trees in the area (both beliefs later proven false), giving rise to an early name for the region the “Ozone Belt”. Regular ferry service commenced across Lake Pontchartrain, and shortly thereafter another resort community was founded, Abita Springs. A railroad was constructed in the 1880s connecting Covington and Abita Springs to Mandeville and to New Orleans, allowing for further growth, particularly in Abita Springs, where underground spring waters permitted supposedly healthful baths.
With the completion of high-speed road connections to St. Tammany from New Orleans and its older suburbs (Lake Pontchartrain Causeway, the I-10 Twin Span), the parish began to develop as a bedroom community. Suburban sprawl first took root in and around Slidell, Louisiana, in the eastern part of the parish. Though the Causeway was completed in 1956 and linked suburban Metairie with western St. Tammany, growth in and around western St. Tammany towns like Mandeville, Covington and Madisonville only gathered momentum in the late 1960s.
While St. Tammany was sparsely populated and almost wholly rural in the 1950s, its population exceeded 200,000 in the wake of Hurricane Katrina’s landfall in 2005.
A major event in the parish’s transition from a bedroom community of commuters to a more diverse and independent economic unit occurred in 2008 with the relocation of Chevron’s regional corporate headquarters from downtown New Orleans to an office park outside of Covington.