approximately 63 cards and covers, lines including North Clark Street, Cottage Grove Avenue, Madison Street, Millard Avenue, Milwaukee Avenue, and Wentworth Avenue, wide variety of interesting covers including Clark Street RPO handstamp used as forwarding mark on 1907 incoming postcard from Japan, Madison Street RPO handstamp on 1899 special delivery cover to Philadelphia, and Clark Street RPO handstamp on 1909 third class cover to Oak Park, generally fine to very fine, a wonderful array of markings represented, such a collection would be very difficult to replicate and could serve as the perfect foundation for an exhibit, see discussion in Piszkiewicz (pages 323-31)