American Airlines is adding 10 new, returning and seasonal routes to Austin and introducing four new codeshare routes with West Coast International Alliance partner Alaska Airlines to that city for flights beginning May 6. The new Austin service and new codeshare routes will be available for purchase March 15. With the anticipated increase in business travel this summer, American is adding twice-daily service from Austin to Las Vegas, Nashville, Raleigh-Durham and Washington Dulles. The airline is also adding daily service from Austin to New Orleans, Orlando and Tampa. New seasonal routes will connect Austin with Aspen, Colorado; Los Cabos, Mexico; and Destin-Fort Walton Beach, Florida. As a result, this summer American and its partners — JetBlue, Alaska Airlines, and British Airways — will serve 19 of the 25 largest markets from Austin.  American and Alaska will continue to enhance their relationship with new codeshare routes from Austin to San Diego, San Francisco and Portland, Oregon, and will introduce domestic codeshare on service between Austin and Seattle with intentions to code on recently announced service from Austin to Boise.  American and JetBlue also recently launched their codeshare, which includes service between New York (JFK) and Austin.