Most local libraries will have a genealogy and local history page on their website. They'll list a lot of good information there. Also visiting the library, if you're interested in a county or city near you, will have an abundance of resources. I've even had my library order books for a nearby city that I like to research. Counties or cities that have historical societies, or tourism information online or that you can visit are also good resources. Also, many books on the history of a state will have sections on the history of particular counties. For example, The Encyclopedia of Kentucky will list many sections on counties that give you a basic concept of important people or places. I've had a great deal of luck by going to google books and typing in the city or county that I'm looking for information on, and often a great deal of books that you can either download for free or read the preview of will come up. Using the search box in the left hand side, I'm able to search for keywords that might give me the information I'm looking for.