I sent this response to Felisa, but since there might be other researchers interested in St. Jospeph the response to jer is below.
Asa general note...rabbis tend to be a good source of information about local Jewish communities. They may not have all the info, but they know where to look and who has knowledge....
Hi Felisa,
I was the rabbi at Temple Adath Joseph in St. Joe from 1995 to 1999. At one time there was a good sized Jewish population with several active synagogues. Currently only Temple Adath Joseph remains. The congregation has a Facebook page.
The St. Jospeh public library has a genealogy page on its website that includes city directories.
There is also a northwest Missouri genealogical society that has a website.
The challenge is the fact of whether or not your ancestors were present when the records were collected.