This is a list of the 127 class 1 railroads in the 1950s as defined by the I.C.C. These railroads had revenue over $1,000,000 per year, and does not include terminal railroads. Several of these are just paper railroads which are owned by another class 1 railroad. Until 1967 Texas had a law that any railroad operating there had to be headquartered in the State. I have included several other railroads (without numbers) for various reasons.
One benefit of having 127 class 1 railroads in the 48 contiguous States was that most of the States had their own interesting list of class 1s.
Class 1 Railroads operating in each State during 1950-
Alabama- AGS, ASAB, ACL, CG, GMO, IC, LN, NC, SLSF, SAL, SOU, WA
Arizona- ATSF, SP
Arkansas- RI, IC, KCS, LA, MV, MP, SLSF, SSW, TP
California- ATSF, GN, NWP, SN, SP, UP, WP
Colorado- ATSF, CBQ, RI, CS, CW, DRGW, MP, UP
Connecticut- CV, NH
Delaware- BO, PRR, RDG
Florida- ASAB, ACL, FEC, GF, GSF, LN, SLSF, SAL, SOU
Georgia- AWP, ACL, CG, CWC, GA, GF, GSF, LN, NC, SAL, SOU, WA
Idaho- MILW, GN, NP, SI, UP
Illinois- ATSF, BO, CO, CEI, CIM, CNW, CBQ, CGW, CIL, MILW, RI, EJE, ERIE,
…GTW, GMO, IC, ITC, LN, MSTL, SOO, MP, MI, NYC, NKP, PRR, SSW, SOU
…TPW, WAB, WC
Indiana- BO, CO, CEI, CIL, MILW, EJE, ERIE, GTW, IC, LN, NYC, NKP, PRR, SOU, WAB
Iowa- ATSF, CNW, CBQ, CGW, MILW, RI, CMO, GN, IC, MSTL, TPW, UP, WAB
Kansas- ATSF, CBQ, CGW, RI, KCS, KOG, MV, MKT, MP, SLSF, UP
Kentucky- BO, CO, CBQ, CIL, CNTP, CRR, GMO, IC, LN, NC, NYC, NW, PRR, SOU, TC
Louisiana- ATSF, RI, GMO, IC, KCS, LA, LN, MP, NONE, SSW, SOU, SP, TNO, TP
Maine- BAR, BM, CN, CP, MEC
Maryland- BO, NW, PRR, WM
Massachusetts- BM, CV, NYC, NH
Michigan- AA, BO, CO, CNW, MILW, DM, DTS, DTI, DSA, GTW, LSI, SOO, NYC,
…PRR, WAB, WC
Minnesota- CNW, CBQ, CGW, MILW, RI, CMO, DMIR, DWP, DSA, GN, GBW, IC,
…MSTL, SOO, NP, WC
Mississippi- A