Marengo, Iowa. $20 1875. Fr. 434. The First NB. Charter #2484. PMG Very Fine 20.This is just the second First Charter $20 to be discovered from this large size only Marengo bank. This mid-grade note features exceptionally bold penned signatures and cherry red overprint inks. The back design featuring the vignette Baptism of Pocahontas is sharply printed and excellently detailed.