There are three different styles of postcards here, but all say to use a one cent stamp, so all are from before 1951, when the price was raised to two cents. They are also all from after World War II.
This card has a linen finish, which theoretically makes it older than some of the other cards. But it was probably available in the same years as the other cards shown here.
Another linen postcard.
This is the only card that is postmarked, having been mailed in 1948 from Chicago to Cleveland. It is also the only perforated card. The message says “Having a wonderful trip. Seattle is beautiful, as is Portland,” so it was probably written during a train trip from Portland to Chicago.
Here’s another view of the Challenger Inn on a more modern, chrome postcard. The back, however, is a cheap paper that yellows, unlike the paper used in postcards from the late 1950s and 1960s.
The cards above and below are the same style as the previous card.