Conducting genealogical research in the United States requires an understanding of county and New England town boundaries. Both usually changed several times before stabilizing. Unfortunately, no complete list of all present and defunct United States counties has been published. The three standard listings of counties in the United States are George B. Everton, Sr., The Handy Book for Genealogists (Logan, Utah: The Everton Publishers, 1988); Ronald V. Jackson, Encyclopedia of Local History and Genealogy: U.S. Counties (Bountiful, Utah: Accelerated Indexing Systems, 1977); and Joseph Nathan Kane, The American Counties: Origins of Names, Dates of Creation and Organization Data, and Published Sources, 4th ed. Metuchen, N.J.: Scarecrow Press, 1983). Everton and Jackson omit many defunct counties; Kane lists only surviving modern counties.

The amount of material published regarding county boundary changes varies widely by state. This material ranges from outstanding books that map the boundaries, such as for California, Indiana, and New Jersey; to listings of laws on boundary changes (without maps), as for Virginia and North Carolina; to practically nothing. Many titles appear in the bibliography by William Thorndale and William Dollarhide, Map Guide to the U.S. Federal Censuses, 1790-1920 (Baltimore: Genealogical Publishing Co., 1987). The Map Guide also shows county boundary changes for all states and territories, but only at ten-year intervals. For state and territorial lines only, see Franklin K.Van Zandt, Boundaries of the United States and the Several States (Geological Survey Professional Paper 609. Washington, D.C.: Government Printing Office, 1976).

Chicago_s Newberry Library, with funding from the National Endowment for the Humanities, has initiated a project to draw all county boundary changes since 1788. It has completed more than fourteen states in five volumes: John H. Long, ed., Historical Atlas and Chronology of County Boundaries, 1788-1980 (Boston: G.K. Hall, 1984). These volumes are a vital resource for the genealogist doing extensive research in those states.

A parallel project of The Newberry Library is the creation of a multi-volume series titled Atlas of Historical County Boundaries. Publication commenced in 1992, with plans to produce one volume per state (except for very small states, such as Delaware, which will be combined with adjacent states). Each volume will include chronologies; separate, detailed maps for each county_s different configurations; county areas; tables of censuses; state outline maps for the censuses; and a bibliography. A list of current volumes is available from The Newberry Library, 60 West Walton, Chicago, IL 60610.