If I have a city and state without a county I use five underscore characters (_____) as a substitute until I can figure out the county. Here is an example: Hatfield, _____, Pennsylvania, USA.
You would be really surprised how many times this situation has come up. I use the GNIS system to search and find counties. If there are duplicate counties for the same city then I usually keep the underscore characters until a bit more research be done and the correct county can be chosen.