Maps are an essential element of any genealogical research. This blog will touch on three types of maps used in your research. They are:
Plat and land ownership maps
Plat maps are designed to shows the metes and bounds of a parcel or section of land. 
|Chesterfield County, SC - DB 6:151-153|
Whereas the ownership map is designed to show ownership, the map below is a: Chesterfield County 1825 Landowner Map surveyed by John Lowery in 1819. 
County Boundary Maps
The best example of County Boundary Maps are contained within “The Handybook for Genealogist” published by The Everton Publishers, Inc. 
|Source: Google Images|
You can view an interactive county boundary map that will redraw based on the data you enter here: http://randymajors.com/p/maps.html 
Show U.S. county boundaries near as of
Mind mapping is a new phenomenon in genealogy research that I believe will continue to rise in use and popularity as genealogists become more innovative in using this tool.
One of the nation leading genealogist Elizabeth Shown Mills did an article on mind mapping that can be found here - Quick Lesson 6 
I did an introductory article that can also be found here - Mind Mapping
This blog mentioned three types of maps used in your genealogical research. There are others that you may find useful in your search such as Topographical maps. Regardless don’t limit yourself to just new maps; over time place name change and an old map may be the only resource for verifying an ancestor location many years ago.
Ancestry has several listing for maps on their website.
They can be found under - Maps, Atlases & Gazetteers
A listing of their holding; you must be a subscriber to the website to view.
· Gazetteer of the state of New York : embracing a comprehensive view of the geography, geology, and general history of the state
There are also many free websites with access to Maps, Atlases & Gazetteers. Do a Google search using these three words - Maps, Atlases & Gazetteers - sit back with a glass of your favorite beverage and enjoy the Maps.
 Chesterfield County, South Carolina, Land Deed - Book 6: pages 151-153, David W. Graves to Malcolm Decker, 28 March 1877, Register of Deeds, Chesterfield, Chesterfield County, South Carolina.Short Footnote:
 David Rumsey Historical Map Collection - http://www.davidrumsey.com/
 George B. Everton Jr., The Handybook for Genealogist: United States of America, Eight Edition (Logan, Utah 84321: The Everton Publisher, Inc., 1991), M-37. Historical U.S. County Boundary Maps - http://randymajors.com/p/maps.html
 Elizabeth Shown Mills, “QuickLesson 6: Mindmapping Records,” Evidence Explained: Historical Analysis, Citation & Source Usage (http://www.evidenceexplained.com/content/quicklesson-6-mindmapping-records : [1 May 2013])