| 1 | MKC | Mak-Air | | MK | AVCODES |
| 2 | MKC | McKeesport Connecting R.R. Co. | 1/1946-7/2005 | | NAKINA |
| 3 | MKC | McKeesport Connecting R.R. Co. | 1/52-7/2000 | | NRHS |
| 4 | MKC | MCKEESPORT CONNECTING RAILROAD CO. | | | PWRC |
| 5 | MKC | McKeesport Connecting Railroad | | | RSRV |
| 6 | MKCB | MUELLER TRUCKING COMPANY | | | SCAC4 |
| 7 | MKCE | MKC ENTERPRISES INC | | | SCAC4 |
| 8 | MKCG | MAK CARRIERS INC | | | SCAC4 |
| 9 | MKCH | MK CARTAGE LTD | | | SCAC4 |
| 10 | MKCL | MAVRAK COMPANY LLC | | | SCAC4 |
| 11 | MKCO | MORRISON KNUDSEN CORPORATION | | | PWRC |
| 12 | MKCO | M K TRUCKING INC | | | SCAC4 |
| 13 | MKCS | MILWAUKEE-KANSAS CITY S. JOINT AGENCY | | | PWRC |
| 14 | MKCS | MUNKITTRICK TRANSPORT INC | | | SCAC4 |
| 15 | MKCT | MAESTRA LINE TRUCKING | | | SCAC4 |
| 16 | MKCX | Morrison Knudsen Corp. | 7/2000-7/2005 (not listed) | | NAKINA |
| 17 | MKCX | Michigan Chemical Co. | 7/1923 | | NAKINA |
| 18 | MKCX | Morrison Knudsen Corp. | Jul-00 | | NRHS |
| 19 | MKCX | *MICHIGAN CHEMICAL CO. | | | PWRC |
| 20 | MKCX | +MORRISON KNUDSEN CORPORATION | | | PWRC |
| 21 | MKCX | Morrison Knudsen Corporation | | | RSRV |
| 22 | MKCX | MORRISON KNUDSEN CORPORATION | | | SCAC4 |
| 23 | MKCY | MACKENZIE | | | SCAC4 |
