There are quite a few maps and resources that are available to help, but here are three references that can certainly get you on your way to success:
- Here is a nice article from Amy Johnson Crow of ancestry.com that can get you started. Why You Need to Learn About Changing County Boundaries. Check out the "Red Book" that she references and follow the instructions for information on each county.
- Another fun resource is from mapofus.org. As an example, follow the link for Alabama and scroll down to "Interactive Map of Alabama Formation". You can scroll through the map year by year or click on a specific year and see what changes to county boundaries have occurred visually. You can select a different state from the left sidebar.
- Yet another useful tool is The Newberry Library's Atlas of Historical County Boundaries. Try this also.
I am sure that there are others, but these are three tools that I have used in the past.
Please add any resources that you have found helpful in the comments.
Happy boundary hunting!