In PA:
(a) Requirement of retention-Every institution and every national bank
located in this Commonwealth shall retain in such form and manner that they
may be readily produced upon proper demand each record of original or final
entry, and each deposit or withdrawal slip or ticket, for a period of seven
years from the date of the making of the last entry thereon, except that
coupons accompanying deposits in a club account, such as a Christmas club or
a vacation club, need not be so retained for more than two years from the
date of closing of such account.
I also thought there was something in BSA requiring retention of deposit slips where there is at least $100 in cash deposited, but I can't find it.