| Milwaukee Road class ES-1 | |
| Powertype: | Electric |
| Builder: | General Electric |
| Serialnumber: | 4986 |
| Builddate: | April 1915 |
| Totalproduction: | 1 |
| Aarwheels: | B-B |
| Uicclass: | Bo′Bo′ |
| Electricsystem: | 1,500 V DC |
| Poweroutput: | 316hp continuous |
| Locoweight: | 98900lb |
| Operator: | Milwaukee Road |
| Operatorclass: | ES-1 |
| Retiredate: | November 1939 |
The Milwaukee Road's class ES-1 comprised a single electric switcher locomotive built in 1915. It was designed to run on the unique 1,500 V DC electrification in the yard at Great Falls, Montana. It was originally numbered #10000 and was numbered E85 in March 1939. It was retired in November 1939.