Whitney Bank is adding six new locations in St. Tammany Parish after acquiring Covington-based Parish National Bank in a $165-million deal late Sunday night.

The merger, which gives Whitney 11 St. Tammany offices, including two new branches each in Covington, Slidell and Mandeville, is part of a push by Whitney to enter into one of Louisiana’s fastest developing banking markets.

“The Northshore community is one of the fastest growing in the state, and Parish National has been a leader in that community for the past 40 years,” said John C. Hope, III, Whitney chairman and CEO. “The merger with Parish National is a first step to achieving the expansion goals we set in our updated strategic plan.” In all, Whitney is acquiring 11 PNB locations on the Northshore, including those in Tangipahoa and Washington parishes.

The deal also includes four locations on the Southshore, a branch in Destin, Fla., and a loan production office in Fairhope, Ala.

Whitney already has five branches in St. Tammany Parish, one in Hammond, 14 in New Orleans and 17 in Jefferson Parish. The merger gives Whitney 182 branches in the five Gulf Coast states in which it operates.

“We are glad to be joining a storied Louisiana institution such as Whitney,” Gary Blossman, PNB president and CEO, said. “Whitney has served the Southshore of the greater New Orleans market for the past 125 years, and we are pleased to become part of the organization as they expand their franchise on the Northshore of Lake Pontchartrain.”

Blossman and other PNB administrators will retain their positions as head of Whitney’s new Northshore region, said Tammy Gennusa, senior vice president of marketing and sales for Parish National Corp.

“The name is changing, but the faces will remain the same,” she said. “There is no indication there will be any job eliminations of any sort.”

Whitney inked the $165-million deal Sunday evening and announced it Monday morning. By early Monday afternoon, Whitney stock dipped 1.2 percent to $20.90 per share on the New York Stock Exchange.

Under the deal, shareholders will receive up to 60 percent of the $165-million merger in cash. The remainder will be paid in Whitney common stock.

Parish National will continue to operate independently until the merger is finalized with stockholder and regulatory approvals in the fourth quarter of 2008.

As of March 31, Parish National Corp. boasted $763 million in total assets.

Whitney Holding Corp., through its banking subsidiary Whitney National Bank, serves the five-state Gulf Coast region stretching from Houston, across southern Louisiana and Mississippi, to central and south Alabama and east to the Florida panhandle. Whitney also owns banks in Tampa, Fla.