KEY WEST, Florida Keys — The long-awaited new terminal building at Key West International Airport has opened to serve departing passengers.

Its opening marks a milestone in the $31.6 million construction and renovation project that will more than double the size of the previous airport.

The new building measures approximately 30,000 square feet and is elevated over parking. It features second-level ticketing, baggage and security areas for departing passengers, restrooms, concessions, a second-level walkway, an escalator and elevator. A restaurant with huge windows offers views of arriving and departing aircraft, and artwork by local artists is to be installed.

“It’s going to give not just those who live here, but the many thousands of visitors to Key West, the luxury of space and amenities,” said Monroe County Director of Airports Peter Horton. “It really has brought this airport into the 21st century.”

Parking for 300 vehicles is located at ground level beneath the new building — 150 spaces for rental cars and 150 for the public.

Among the departing passengers Wednesday morning were Stanley Kovak of Wilton, Conn., and his 7-year-old English springer spaniel Parker, both regular winter visitors to Key West.

“Using this airport is so much more comfortable — a lot more spacious than the other terminal,” said Kovak.

Construction crews are expected to begin renovating the existing 1957 airport building soon. When that project is complete, the 24,000-square-foot building will feature a passenger arrival and baggage claim area with rental car counters, restrooms and a baggage service office. It will also house a 200-seat departure lounge with restrooms and a 160-seat restaurant and tavern.

Renovation to the existing terminal is scheduled for completion in early June. The airport remains fully operational throughout the construction project.

About 450,000 passengers arrive and depart Key West International Airport annually. Up to 60 commercial flights operated by five commercial carriers — including arrivals and departures — are scheduled daily.