An accompaniment to Mitchell's reference and distance map of the United States : containing an index of the various counties, districts, parishes, townships, towns, etc., and an index of the rivers : together with a geographical description of every state and territory in the Union : also an accurate synopsis of the population in the year 1840 according to the sixth census, alphabetically arranged : in addition to which there are a variety of statistical aggregates, accounts of railroads and canals, colleges, &c., and a synopsis of the new postage law.