. (Railroads) A unit of measurement of the passenger transportation performed by a railroad during a given period, usually a year, the total of which consists of the sum of the miles traversed by all the passengers on the road in the period in question. [ Webster 1913 Suppl. ]
. (Railroads) Passenger miles collectively; the total number of miles traveled by passengers on a railroad during a given period. [ Webster 1913 Suppl. ]