The demand for them is what is causing the long waits. They are stored at the PA State Archive in Harrisburg where one can visit to view them, but there is a limit to 5 at one time and two such orders per visit. It takes almost two hours to have them pulled and brought down to the reading room. A normal box of research material (historical documents) used to take about 15 minutes to obtain. That should give you some idea of the demand.