As recently as 1970 United Airlines offered men only flights wrote Gary Leff:

• The flights operated between the New York-Chicago and Los Angeles-San Francisco business districts.
• Both women and children were banned from the planes except, of course, for the air hostesses who would light the men’s complimentary cigars.
• “Last minute message service” was offered, allowing passengers to have the airline make a call to the office on their behalf.
• The flights also had a teletype update service to provide passengers with closing market numbers.
• One possibly apocryphal story from the era suggests that when wives of frequent travelers on the men only flights were asked about the flight, the most common response was “what flight?”

See ads for the flight from the era, and read more over here.

Source: View from the Wing

Via: Marginal Revolution