Austin-Bergstrom International Airport’s South Terminal is closing for good at the end of the month as a massive airport expansion moves forward.

The detached, remote terminal will shutter March 31, airport officials announced Tuesday. Starting April 1, Allegiant Air and Frontier Airlines — which operate out of the South Terminal — will move to the main Barbara Jordan Terminal.

“And no, this is not an April Fool’s joke,” reads a statement from the airport.

Passengers flying Allegiant or Frontier through March 31 should head to the South Terminal, and those departing April 1 or later should go to the Barbara Jordan Terminal. Passengers who leave Austin before April 1 and return afterward will depart from the South Terminal but arrive back at the main terminal. Shuttles between the two terminals will temporarily continue to operate after the transition so anyone parked in the South Terminal parking lot before April 1 can retrieve their vehicles.

The three-gate South Terminal opened in 2017 to accommodate growing demand. The building will be razed to make way for new midfield taxiways to support the airport’s forthcoming second concourse, which is scheduled to open in the early 2030s. The Federal Aviation Administration has pledged $108 million to build the taxiways.

“Simply put, this step helps us prepare for the future of travel in Central Texas,” the airport’s statement reads.

When the city opened the South Terminal, it signed a 40-year lease with LoneStar Airport Holdings to operate it. In 2023, the city settled a pair of lawsuits for $88 million to terminate the lease and greenlight the terminal’s demolition.

The new Concourse B and renovations to existing terminal space will add 32 gates to the airport in the coming years as part of the $5 billion “Journey with AUS” expansion program. Twenty-six of the new gates will be in the future midfield concourse, which will connect to the existing terminal by an underground walkway.

A new temporary facility known as Concourse M is expected to come online next year, adding six gates to maintain capacity as construction disrupts operations in the Barbara Jordan Terminal. A bus will take passengers between the buildings.