Congressional Districts in Pennsylvania are set by law, and therefore the redistricting plan must be passed by the General Assembly and signed by the Governor. This usually must be done by late January of the year after the Census data is released (in this case, January of 2012), when paperwork begins for candidates in the spring primary elections.The General Assembly has repeatedly missed this deadline in past redistrictings, wreaking havoc for candidates and election officials and forcing the courts to step in and force the process to a conclusion.
The apportionment of members of the House of Representatives is mandated by the Constitution, but given the importance of the process, it is surprising how little the document actually specifies. Article I, Section 2 calls for a Census every 10 years. It also calls for representatives to be apportioned equally among the states based on population (the original formula notoriously called for slaves to be counted as 3/5 of a person each, although that was changed by the 14th Amendment after slavery was abolished). The Constitution does not even require that House members be elected based on geographic districts, nor does it say how any such districts should be determined.
By tradition, most states used the district system to select members of Congress, and it was made a legal requirement for all states in 1967. (There are seven states that have such small populations that they have just one representative; redistricting is therefore a moot question). To prevent Congress from expanding to an unwieldy size, Congress set a limit of 435 members of the House in 1911. Pennsylvania has been steadily losing power in Congress ever since as population moved South and West - down from its peak of 36 in 1910 to 19 in 2001.
NOTE: Dates are approximate and subject to change.
Compiled by Committee of 70
Committee of Seventy + 
