▁etc . ▁used ▁to ▁cancel ▁a ▁post age ▁stamp . ▁ ▁Ne ither ▁should ▁a ▁post mark ▁be ▁confused ▁with ▁over print s ▁generally , ▁or ▁pre - can c els ▁( st amps ▁that ▁have ▁been ▁cancel led ▁before ▁the ▁en velope ▁or ▁package ▁to ▁which ▁they ▁are ▁aff ixed ▁is ▁submitted ▁or ▁depos ited ▁for ▁accept ance ▁into ▁the ▁mail stream , ▁they ▁most ▁commonly ▁have ▁taken ▁the ▁form ▁of ▁a ▁pre - print ed ▁city ▁name ▁on ▁the ▁stamp ) ▁specifically , ▁which ▁generally ▁do ▁not ▁indicate ▁a ▁date . ▁ ▁Fl ight ▁c ach ets , ▁more ▁or ▁less ▁elaborate ▁rub ber - st amps ▁on ▁an ▁en velope ▁indicating ▁on ▁which ▁flight ▁( typ ically ▁a ▁first ▁flight ), ▁a ▁first ▁flight ▁cover ▁has ▁tra ve led ▁via ▁air mail , ▁are ▁in ▁addition ▁to ▁the ▁post mark ▁and ▁are ▁not ▁post marks ▁either . ▁ ▁The ▁visitor ▁cent ers ▁at ▁U . S . ▁national ▁par ks ▁also ▁have ▁a ▁post mark - like ▁in ked ▁rub ber ▁stamp ▁available ▁to ▁stamp ▁into ▁a ▁book ▁of ▁park ▁st amps ▁( the ▁Pass port ▁To ▁Your ▁National ▁Park s ) ▁or ▁a ▁post card , ▁or ▁any ▁piece ▁of ▁paper . ▁This ▁is ▁set ▁to ▁stamp ▁the ▁day ' s ▁date ▁in ▁the ▁middle ▁and ▁the ▁park ' s ▁name ▁and ▁location ▁around ▁the ▁edge ▁like ▁many ▁post marks , ▁though ▁it ▁is ▁not ▁used ▁for ▁post age ▁purposes . ▁ ▁Club s ▁ ▁There ▁are ▁many ▁clubs