Nice postcards.
Some names from the first postcard can likely be seen in the clipping below for Newark Valley. This is from a Binghamton newspaper, so that adds up.
Here is a link for some information on the Oneonta postcard:
https://diamondimages.photoshelter.c...000OnLtxUA6oVE
The East Branch postcard is probably from New York as well. It's not dated that I see, but looks to be from the same era. I can't say much else about that one.
They certainly have some value. The Oneonta postcard seems to have a few guys that had a cup of coffee in the majors, so there is value there. You would have to confirm names for significant value on the others. In the general range of $25-$75 for each? Maybe a little more or less depending on the postcard. The lower part of that range would probably be East Branch, then Newark Valley, and finally Oneonta towards the top. That's just my opinion, you never know what someone is willing to pay though. Finding a big name is usually the key to these type of postcards.