The Pennsylvania Supreme Court has amended this rule to allow attorneys to practice in all counties.
In Re: Amendment to Rule 14 of the Rules of the Supreme Court of Pennsylvania, 419 Pa. (5), ___ A.2d ___ (1965).
Pennsylvania Practice and Procedure - Principal Office Rule,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol4/iss3/12