US Airways, which merged with American Airlines in December of 2013, will no longer exist after it takes its final flight late tonight into Saturday morning.

Flight 1939 – coinciding with the year the airline was founded – took off this morning from Philadelphia, a US Airways hub. It then flew to another hub in Charlotte, was scheduled to depart for Phoenix this afternoon, and then fly on to San Francisco.

At SFO, it was scheduled to make its last takeoff at 9:55 p.m. PT on a redeye back to Philadelphia, landing at 6:18 a.m. ET.

Another big US Airways hub, Pittsburgh, saw its final flight in August. The airline not only had an extensive presence at the airport that included an operations center in Moon Township that employed 650 workers, but it began its life as All American Aviation in western Pennsylvania in 1939.

After tomorrow morning, the US Airways name then goes the way of Northwest and Continental, two airlines that merged with Delta and United, respectively, in the last decade.

Its website will shutter, and the US Airways reservation system will go dark.

This merger grows American Airlines by more than 30 percent, making it the biggest airline in the world. To prepare for any problems with reservations – such as the disaster that took place when United and Continental merged – American says it has run 5 million mock reservation combinations on more than 9,000 computers and has spent more than 1 million hours training its employees.

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