The postcard was addressed to Pauline and Theresa Leisenring and was sent out on July 4, 1943, from Rockford, Ill., the Elmira (N.Y.) Star-Gazette reported.
It was sent by their parents, who were visiting their brother at the Medical Center Barracks at Camp Grant.
The card reads: "Dear Pauline and Theresa, We arrived safe, had a good trip, but we were good and tired. Geo. looks good, we all went out to dinner today (Sunday). Now we are in the park. Geo has to go back to Grant at 12 o'clock tonight. Do not see much of him. We are going to make pancakes for Geo for supper tonight. See you soon. Love Mother, Dad."
However, it just arrived last week at the home of Adam and Laura Rundell.
"It was delivered in mint condition. We were so shocked," Laura said. "It's a treasure that just showed up in the mailbox with our address on it."
"We hear about things like this happening every once in a while," said Karen Mazurkiewicz, a spokeswoman for the U.S. Postal Service in Buffalo. "Generally, if old mail pieces are uncovered in a postal facility, they are put in the mail with information about where the items are found."
Theresa died in 1954, Pauline in 1962. The Rundells said they did a little research and found some relatives of the late Leisenrings.
"We offered the postcard to them," Adam Rundell said. "They seemed interested but so far haven't picked it up."