MIAMI — Frontier Airlines announced 12 new year-round and seasonal routes, expanding its footprint in Colorado Springs and Las Vegas.

The ultra-low-cost carrier revealed that the cities receiving the new service include Bismarck in North Dakota, Chicago, Colorado Springs, Indianapolis, Las Vegas, Los Angeles, San Diego, San Francisco, Sioux Falls in South Dakota and Washington Dulles. Later this fall, it will add new flights from Colorado Springs to Fort Myers and Tampa, Florida.

Flights from Colorado Springs to San Diego, Washington Dulles, Los Angeles, Chicago O’Hare, and San Francisco will start in June and July. Frontier will also offer daily frequencies on the Washington, San Diego and Chicago routes while flying the Los Angeles and San Francisco routes four and three times per week, respectively. Service to Tampa and Fort Myers will start in the fall, although dates have not been confirmed.

The new service is a significant expansion for Frontier in Colorado Springs, where it began service last year with three routes. Previously, the carrier made Colorado Springs a focus city in 2012, but it pulled out by mid-2013, before returning again in 2016.

Frontier will compete with United on the Los Angeles, San Francisco and Chicago routes, and it will be the first carrier to serve Washington Dulles, San Diego and the Florida destinations from Colorado Springs.

Out of Las Vegas, Frontier will start year-round service to Indianapolis, Washington Dulles, Bismarck, and Sioux Falls. Indianapolis flights will operate three times per week, Dulles daily, Sioux Falls four times per week and Bismarck twice per week.

Frontier will compete against Allegiant on the routes from Las Vegas to the Dakota cities, against Allegiant and Southwest on the Indianapolis route and against Southwest and United on the Dulles route.