This website offers the most comprehensive listing of research resources available for Butler County. Also links to PA online indexes for births and deaths. 
               Complete Birth Records 1893-1905
               Indexes to the Deaths 1893-1905, Estates1800-1910+, Naturalizations 1800-2000 
               The complete 1883, 1895 Histories of Butler County and the biographical index to the 1909 history of Butler County
               Early Butler County Landowner maps
               Index of Butler County Land Warrants and Patents
               Links to military records and resources like the complete five volumes of PA Civil War regiments by Samuel P. Bates.