From the Delta Heritage Museum website..

Travel Air Carries Delta's First Passengers
Delta Air Service, later Delta Air Lines, launched its first airline service on June 17, 1929, with a Travel Air S-6000B.
The high-wing, five-passenger, single-engine monoplane flew Delta's pioneer route from Dallas, Texas to Jackson, Mississippi (with stops in Monroe and Shreveport, Louisiana).
Dallas-Jackson: 5 hours, 427 miles, ticket cost $47.25 ($90 roundtrip).
These "limousines of the air" were steel frame construction covered with a "skin" of linen and epoxy. Delta's livery was a sleek black and International Orange paint job. "Deluxe" insulated, wood paneled cabins featured woven wicker seats, and hand holds rather than seat belts. Passengers could lower the Travel Air's roll-down windows for ventilation.
Designed to carry four passengers and two pilots. Because Delta flew with one pilot, a fifth passenger could also sit in the co-pilot seat.
Carried up to 150 pounds of baggage.
Price when new: approximately $13,500