Southwest Airlines, the largest carrier at Baltimore-Washington International Thurgood Marshall Airport, announced Monday that it would add additional summertime flights to eight cities around the country — and plans to add more flights in the future.

The Dallas-based airline is adding an extra flight each day to Hartford, Conn., and to Orlando and Tampa, Fla. Southwest will also add an extra daily flight to Denver, Manchester, N.H., and Oakland, Calif., from Sunday through Friday. And Nashville, Tenn., and Seattle will get an extra daily flight on Saturdays from BWI.

The flights will run from June 5 through Aug. 6; tickets went on sale Monday.

“This is about enhancing our breadth of service and adding convenience for our Baltimore-Washington area customers as we seek to grow in the entire region,” Andrew Watterson, Southwest senior vice president for network and revenue, said in a statement. “Collectively, Southwest offers more service from BWI, Reagan National, and Dulles Airports than any other airline.

Watterson said the airline is “just getting started.”

Ricky Smith, the CEO of BWI, said in a statement that the new flights would expand consumer options.

“Southwest continues to provide outstanding customer service and low fares for our customers,” he said.

The announcement likely will sustain recent growth at BWI. The airport set a record for traffic with 23.8 million passengers in 2015, an increase of 6.8 percent over 2014.

That bump was driven largely by an increase in international passenger traffic, which grew 31.9 percent in 2015. Total international passengers in 2015 climbed to 1.14 million, the first time that figure was greater than 1 million passengers.

Southwest launched international service from BWI in July 2014, starting with flights to Aruba; Montego Bay, Jamaica; Nassau, Bahamas; Cancun, Mexico; and Punta Cana, Dominican Republic. In 2015, Southwest began service from BWI to San Jose and Liberia in Costa Rica and to Cabo San Lucas, Mexico.

Southwest CEO Gary Kelly said last year that BWI would be a hub for the airline's international expansion.

The airline also has continued to expand its domestic service. Last month, Southwest announced it would add daily service between BWI and Sacramento, Calif., starting in August. Two new daily flights to Minneapolis-St. Paul, Minn., start April 12.

Southwest is the largest carrier at BWI, with 16.8 million passengers in 2015 — more than 70 percent of all flights at the airport. Southwest had 14.9 million passengers at BWI during 2014, and the airport is the carrier's third-largest hub in the country after Chicago Midway International Airport and Las Vegas' McCarran International Airport.

cwells@baltsun.com