Lycoming County, PA
Was created in 1795.
All or part of 17 other counties were hacked off of Lycoming County over the years but it is still the largest county in Pennsylvania. It is now about 1/10 of its original size. (See "The Pennsylvania Mason" Oct 2009 p 17)
Eureka Lodge No.335 is located in Montoursville, PA, which is in Lycoming County.