Delta Air Lines will add more than 100 flights and 29 destinations at New York’s La Guardia by mid-2012 as it builds the airport into a domestic hub and seeks to dominate the nation’s busiest aviation market.

It will be the biggest single expansion by any carrier at La Guardia in “decades,” Delta said yesterday. The airline is spending $100 million at La Guardia as it takes advantage of 132 flight slot pairs gained in a deal with US Airways Group.

Delta’s growth at La Guardia, coupled with a $1.2 billion expansion at John F. Kennedy International Airport, is aimed at winning business travelers who fly more frequently and generally pay higher fares.

Delta rose 5 percent to close at $9.02, paring the shares’ decline this year to 28 percent.