CHICAGO — United Airlines said Wednesday it will buy up to 200 small electric air taxis to help customers in urban areas get to the airport.

The airline said it will help electric-aircraft startup Archer develop an aircraft capable of helicopter-style, vertical takeoffs and landings. Archer hopes to deliver its first aircraft in 2024, if it wins certification from the Federal Aviation Administration.

United said once the aircraft are flying, it and partner Mesa Airlines will acquire up to 200 that would be operated by another company.

According to an Archer presentation to investors, the orders are worth $1 billion, with an option for $500 million more.

Privately held Archer, which is based in Palo Alto, California, announced separately that it has agreed to merge with Atlas Crest Investment Corp. and form a new publicly traded company. Archer and Atlas put a $3.8 billion value on the deal, which sent Atlas shares up 22%.

Archer’s aircraft are designed to fly under battery power for up to 60 miles at speeds of up to 150 mph.