These cards are also known as the Humorous Dressed Cats postcards or Mainzer Dressed Cats postcards. They were originally published from the 1940's through the 1960's by Alred Mainzer Inc. in New York City. These cards are now being reprinted in Spain, Thailand, Belgium and Turkey. The artist was a European graphic artist by the name of Eugen Hartung (or Hurtong) who lived from 1897 - 1973.
These postcards make for a great collection. I have seen them matted and framed at craft shows. Get several with a similar theme to make a wonderful gift.