Here is a posting by Amanda Forson from the WorldVitalRecords.com newsletter.
Go to Mapquest.com and look up the town where an ancestor lived and look at surrounding towns in greater and lesser detail. Mapquest now provides counties as part of its search capabilities. The present-day maps will give you an idea of where to begin looking for information for previous time periods.
Once you get the county information, go to the Handybook for Genealogists and look up the county in question to see what the county was during the time period needed. (Not every county had the same boundaries or the same name as it currently does “back then.”) If you need to purchase a copy of the Handybook, this can take a few minutes. After logging in to WorldVitalRecords.com, go to the Store. (We recommend the Handybook as an industry-standard book for finding geographical information.)
Look up the historical societies associated with the current county and the previous county on Google as each society may offer different information that could be pertinent for searches. Browse their site and see what is offered.
Contact the historical societies found in Day 3 using email addresses and/or contact information provided. Whenever possible (and funds allow), join the historical society.
Look in FamilySearch.org’s Family History Library Place Search for information concerning the area in question.
Check for newsletters and journals dealing with genealogy for the country, state or province, county or district, city, town, boroughs, etc. One place to look would be in the Library of Congressâ€¦ What genealogical periodicals do they keep? See here.
Check WorldVitalRecords.com for new geographically-focused information by using the drop-down menu under Databases. Also check the alphabetical listing shown below the All Databases section for places close to where an ancestor lived or places along the way of migration routes.