Dave, I received this from a class that I took in Genealogy. The Effective date is determined by the Federal Government - -Census Bureau. Alot of good information is on Brenda's Guide to Pa. Genealogy. Address is http://www.chartiers.com/pages/palinks.html When Brenda's page comes up click on FRAMES. Dee turekd08@aol.com Researching--SCANLON-BOYD-LEEPER-AMMON