Note: This story was updated 10 a.m. Wednesday

Frontier Airlines has announced  it will fly to Chicago O'Hare, Charlotte, and Atlanta daily from Philadelphia International Airport, beginning March 13.

An introductory fare starting at $19 one-way will be available until 11:59 p.m. Wednesday at for travel on Tuesdays and Wednesdays through April 29.

Fares from $49 one-way will be available on the company's website until 11:59 p.m. Jan. 10 for travel on Mondays, Tuesdays, Wednesdays, Thursdays, and Saturdays through May 16. Seats may be limited, and blackout dates will apply.

"This added service gives travelers in the region access to more low-fare flights to popular destinations," said Philadelphia airport CEO Mark Gale. "More choices mean more competition, which is good news for the consumer."

The Denver-based airline began flights in December from Philadelphia to Miami, Orlando, and Tampa, Fla., and Cancun, Mexico.

Frontier has been expanding in large airports, such as Philadelphia, and cutting back in smaller markets, such as New Castle Airport in Delaware.

Frontier has trimmed some unprofitable routes at Trenton-Mercer Airport in Ewing Township, but added flights this winter from Trenton to several Florida cities.

Frontier has three aircraft based in Trenton - the same as last summer - but has trimmed nonstop destinations St. Louis, Milwaukee, Cleveland, Indianapolis, New Orleans, Columbus, Ohio, Cincinnati, and Nashville, locations that did not meet expectations.

"We've learned more about how the Trenton market performs," said Daniel Shurz, Frontier senior vice president. "More Florida in the winter when people want to escape the winter weather, and more non-Florida flying in the summer when the weather is better for those trips."

Trenton flights to Detroit and Minneapolis will return in April, and Frontier will begin flying to Chicago O'Hare from Trenton in April, with the goal of building Chicago traffic and creating more connecting opportunities for customers, Shurz said.

"We've seen a good response in the Philadelphia region to our low-fare product," Shurz said. "Philadelphia airport has a very strong, successful hub carrier," referring to US Airways-American.

"What it doesn't have is much in the way of low fares. We see an opportunity to be in Philadelphia International as well," he said.

Frontier now flies nonstop from Trenton to 10 cities: Atlanta, Charlotte, Chicago-Midway, Raleigh-Durham, N.C., and Fort Lauderdale, Fort Myers, Orlando, St. Augustine, Tampa, and West Palm Beach, Fla.

Frontier announced it will suspend service to Orlando and Tampa from New Castle Airport in April and will fly to at least one Florida destination from Delaware in late 2015.

"Our commitment to Trenton remains firm," Shurz said. The airport is in a heavily populated metro area that includes New York, Newark and Philadelphia.

"In Trenton, we see customers coming from all directions, but a bit more traffic from the New Jersey side of the airport," Shurz said. "The fares at Newark are even higher than they are at Philadelphia International."

"A lot of customers have been priced out of the opportunity to fly," Shurz said. "We see this great opportunity, as we've been able to do in Trenton, to give more customers the opportunity to take the trips they want to take, to take their family on vacation, to go see friends and family."