I bought this postcard partly because of the image of the Gutenberg Bible on the picture side and partly because of the unusual mixed franking on the message side: Scott Germany #646 and United States #982.
The card was written in Mainz on 26 June 1949 and received by the addressee in New York City on 30 June. The only postmark is from NYC Grand Central Station, but the date is unclear, since the final digit for the day ended up right on the perfs. It looks like 26, but that seems unlikely, since the card was written in Mainz on that day; 28 seems more probable to me.
Can someone with a better knowledge of postal rates and practices in postwar Germany explain why this card has dual franking and no German postmark? Is it because the Federal Republic was brand new (established on 23 May 1949) and perhaps not yet recognized by the UPU?