I'm not as "up" on my US stamps as I should be. I have this postacard with a 2c postage due stamp. It is perf 10 x 10, and what I believe to be a bright rose color. Perf 10 x 10 could either be a J53 or J60, and J60, according to my catalog, also includes a rose shade. The J60 was issued in 1916, and this card is also dated 1916. The major difference between the 2 that I can see is that one should be watermarked and one should not, but of course without lifting the stamp I will not be able to tell.
Is there anything else I can look for to tell which this is. The J53 is pretty inexpensive, but the J60 has decent value, so for now I will assume it's the cheap one.