Can anyone help me identify the plane in this photograph? I'd be very grateful for any help in identifying this U.S. plane. Other photos in the album look like they're from WW2.
What you have there is I believe a Boeing Model 80A-1:


Source 


Source

You can read more about it on Wikipedia: Boeing Model 80

The Model 80 air transport aircraft was built in the mid 1920's. It is notable as being the aircraft used for the first flight to feature a flight attendant, which were registered nurses at the time.