High Quality Content by WIKIPEDIA articles! Pan Am Railways (PAR), known as Guilford Rail System (GRS) before March 2006, is a holding company that owns and operates a Class II regional railroad covering northern New England from Mattawamkeag, Maine to Rotterdam Junction, New York. The primary subsidiaries of PAR are Boston and Maine Corporation (reporting mark BM), Maine Central Railroad (reporting mark MEC), Portland Terminal Company (reporting mark PTM), and Springfield Terminal Railway (reporting mark ST); BM and MEC are operated under lease by ST. PAR is a subsidiary of Pan Am Systems, formerly known as Guilford Transportation Industries (GTI). GTI bought the name, colors and logo of the Pan Am airline in 1998. The company headquarters is located in North Billerica, Massachusetts (an unincorporated village within the town of Billerica).