Below is a list of all the locomotives actively tracked on HeritageUnits.com.
Alabama & Gulf Coast Railway
Arkansas Oklahoma Railroad
Atchison, Topeka and Santa Fe Railway
Berkshire Eastern Railroad
California Northern Railroad
Chicago Burlington & Quincy Railroad
Chicago, Fort Wayne and Eastern Railroad
Delaware-Lackawanna Railroad
Georgetown Rail Equipment Company
Great Lakes Central Railroad
Knoxville Locomotive Works
Massachusetts Bay Transportation Authority
Metro North Commuter Railroad
Minnesota Commercial Railway
Missouri & Northern Arkansas Railroad
New England Central Railroad
New York, Susquehanna & Western Railway
North Carolina Dept. of Transportation
Portland and Western Railroad
Railway Service Contractors Inc
Reading Blue Mountain & Northern Railroad
Spokane Portland & Seattle
The CIT Group/Capital Finance, Inc
Twin Cities & Western Railroad