Unfortunately, this postcard gives us little written information beyond the "GONDOLAS IN CENTRAL PARK, NEW YORK" printed in the margin. The number beneath that text is "1985" and I think that's a serial number or some other non date-related code.
I could be wrong, but I'm pretty sure this item predates the 80's I grew up in.
The presence of the Bethesda Fountain in the background indicates that the postcard in question came after 1873 - the year of the fountain's unveiling.
You can read more about the Bethesda Fountain in my post from March 19th, 2008.
The felze di tela on the one gondola clues us in to the likelihood that this is pretty old.
The biggest pieces of evidence in this postcard image can be seen flying prominently from the decks of both gondolas: the Stars and Stripes. The flag on the left isn't very discernible, but the one on the right clearly has it's stars in a perfect grid pattern. Only a few times in our history have the stars in our flag been arranged so, and the only time there were so many, in such a tight pattern, was when we had 48 states. This flag, issued by President Taft, flew proudly for 47 years- from 1912 until 1959 when Alaska became our 49th state. All other "grid-pattern" flags flew for much shorter durations. If this variation of the American Flag looks familiar, it should: it flew during both World Wars, and can be seen in photos and films from, or depicting the period.
I believe this postcard comes from the earlier part of that 47 year period. The Great Depression, which came to the U.S. in 1929, affected a great number of businesses, and I'm guessing that postcard production either slowed or halted at that point. By 1939 the United States and Italy were on opposite sides in World War II - it seems to me that the gondola might not have featured so prominently in tourism at that point. Beyond the war, Postcard quality improved, and other formats (including "real photos") came on the scene. Unfortunately, we really can't speculate based on clothing because there are no passengers in the gondolas and the people in the background by the fountain are too far away. There's no telling whether the gondoliers are in costume or period clothing.
So based on the type of postcard, my guess is that we are looking at an image printed between 1912 and 1929.
I supposed this has been more of a "Postcard Speculation" rather Postcard History Lesson".
You've read my guess, what's yours?