PORTLAND — Airport officials say the number of passengers who used the Portland International Jetport last year jumped more than 3 percent compared to the previous year.

Airport Director Paul Bradbury announced Wednesday that nearly 60,000 additional passengers used the airport in 2013.

He said several factors led to the increase, but a major contributor was the addition of Southwest Airlines service in April.

He says Southwest plans to expand its offerings in Portland by adding new Saturday nonstop service to Chicago’s Midway Airport starting in June. The airline will also add a fourth daily nonstop flight to Baltimore in June.