Rights Movement and a concomitant reaction against cultural liberalism, the Republicans gained strength in the conservative suburbs of New Orleans and Baton Rouge and for a time in Caddo Parish. The GOP drew increasing support among rural voters elsewhere, including parts of North Louisiana and Southeast Louisiana. These patterns follow trends in other southern states as white control of state Democratic Party structures weakened, and the region became more diverse and more prone to adopt the two-party behavior characteristic of most of the nation. In time, Republicanism took root in the Shreveport-Bossier City area of northwest Louisiana, with increasing strength, added from Ouachita, Lincoln, Rapides, East Baton Rouge, and Lafayette parishes plus most of the suburban parishes about New Orleans. One of the small Republican-leaning parishes is La Salle in North Louisiana. Still, another is predominantly white West Carroll Parish. Since the construction of the Lake Pontchartrain Causeway in the mid-1950s, the Northshore Region began demonstrating increasingly Republican leanings, first and most notably in Saint Tammany Parish, which as of 2010 had the highest percentage of registered Republican voters in Louisiana. It was the first parish since the Reconstruction Era to leave the Democrats merely a plurality and the first to experience a Republican majority. In the 1964 election, Republicans won the state by double digits, their largest victory since Reconstruction, as Democratic support collapsed in the Northern part of the state following the passage of the Civil Rights Act of 1964. The Republican victory was not as commanding here as it was in other Deep South states, as they stayed under 60% of the vote. The state soon became a swing state by voting for the nationwide winner in every election between 1972 and 2004. 21st century The political balance in Louisiana was heavily affected by the post-Hurricane Katrina departure from New Orleans. Heavily Democratic New Orleans lost some 1/3 of its population. The overall effect reduced the Democrats' base of support in the state and turned Louisiana into a Republican-leaning state thereafter. New Orleans remained Democratic, electing Mitch Landrieu as mayor in February 2010. In the 2008 elections, Louisiana sent a mixed result, with the election of U.S. Senator John McCain for President and the reelection of Democratic U.S. Senator Mary Landrieu. The other senator, at the time, was Republican David Vitter. Since that election, Republicans have rapidly come to control nearly every federal and statewide office. Both