Start with a Google search for a place. For example, start a search for "Harleysville, Pennsylvania." If you do a search for the town, which is a very small place in Pennsylvania, you will find a lot of references, most of which will be commercial sites like Walmart and real estate companies. The first part of the trick is to add "wikipedia" to your search, so that the search looks like "harleysville pennsylvania wikipedia." Surprise, there is a specific Wikipedia article on Harleysville. The entry says:
Harleysville is a census-designated place (CDP) in Montgomery County, Pennsylvania, United States. The population was 8,795 at the 2000 census. It belongs to the Lower Salford Township. Harleysville was settled by Pennsylvania Dutch in the 1700s.But now comes the real part of the trick, look in the upper right hand corner of the Wikipedia article or somewhere else on the right side. There is an entry for "Coordinates." This gives the latitude and longitude of the featured location. The further surprise comes when you click on the coordinates themselves. Wikipedia then gives you a listing of every map location it can find listing the particular location! In the case of Harleysville, there are well over seventy-five different map locations referenced.
Now, you say, what about someplace really obscure? How about someplace in Europe or Africa? Of course, there are limitations on the information in Wikipedia. You might need to go to the next larger city near the location to find all the maps, but it works an amazingly high percentage of the time.
The next trick involves looking at one of the possible entries on the long list of maps. That is the Geonames Website. This Website contains over eight million placenames that are available for download free of charge. For example, I looked for "Nutrioso" a very small village in Arizona. There are four references all of which take me to maps of that location.
By adding Websites that cross-reference old place names with newer ones, you can spend some time and find a lot of information about the places where your ancestors lived or where they might have lived.