Five Pennsylvania Democrats have filed to be on the Democratic primary ballot for Lieutenant Governor. The primary is May 20. One of the Democrats has challenged the petition of one of the other candidates. See this story. Pennsylvania requires 1,000 valid signatures for that office, with at least 100 from each of five counties.
Pennsylvania is the only state that still has county distribution requirements for statewide candidates, and the distribution requirement only applies to primary petitions for state office, not federal office. County distribution requirements for statewide candidate petitions in all other states have long ago been declared unconstitutional or been repealed. The most important precedent is from the U.S. Supreme Court and is Moore v Ogilvie, issued in 1969.