Charleston International Airport passengers (copy) (copy)

Charleston International Airport is home to the state's busiest terminal with nearly 4 million passengers a year. File/Leroy Burnell/Staff

Charleston International Airport is once again gaining new air service.

Officials will announce Thursday new routes to new destinations. The carrier and destinations have not been released.

A press conference is set for 11 a.m. at the airport.

Several new routes and new airlines have been announced for the state's largest airport during the past few months.

On Feb. 20, low-cost carrier Frontier Airlines of Denver will launch three flights per week on Tuesday, Thursday and Sunday to the Mile High City and Philadelphia. On May 11, it will tack on Monday and Friday flights to Chicago O'Hare International.

Also, Las Vegas-based Allegiant announced in January it will begin seasonal, nonstop service in April between Pittsburgh, Cincinnati and Indianapolis on certain days of the week.

Sign up for our new business newsletter

We're starting a weekly newsletter about the business stories that are shaping Charleston and South Carolina. Get ahead with us - it's free.

Other airlines, including Alaska, Southwest, American and Delta, will add routes throughout the year.

Charleston International ferried 3.98 million people through its terminal last year in inbound and outbound flights.

Check back later for more details.

Reach Warren L. Wise at 843-937-5524. Follow him on Twitter @warrenlancewise.