There are five days designated in state law as school holidays in Pennsylvania.

Then there are “local holidays” that are set by each school board for that school district (school district sizes vary greatly). These local holidays will typically vary based on the composition of the student body. Most of the time though, these are holidays known and celebrated outside of Pennsylvania.

Ref:

“No school shall be kept open on any Saturday for the purpose of ordinary instruction, except when Monday is fixed by the board of school directors as the weekly holiday, or on Sunday, Memorial Day, Fourth of July, Christmas, Thanksgiving, the First of January and up to five additional days designated as local holidays in the adopted school calendar by the board of school directors as official local school district holidays.”

https://www.legis.state.pa.us/cfdocs/legis/LI/uconsCheck.cfm?txtType=HTM&yr=1949&sessInd=0&smthLwInd=0&act=14&chpt=15&sctn=2&subsctn=0