Donna et al, Allegheny County was formed in 1788 out of Washington and Westmoreland for the most part, in 1800 Beaver, Butler, Mercer, Erie, Venango, Crawford, Armstrong, and Warren were formed. Lawrence was formed in 1848. Death certificates were not required in Pennsylvania until 1906. Prior to that some counties and some other political sub-divisions required them and some were voluntary. I do not believe there were any before 1885 or 1886 in this part of the state. The best source before that time would be family bibles, church, cemetery, and newspaper records. Mac