If you are landlocked, and you are running steam, you would need some sort of qualification to do so. In New Jersey, you would need to be tested for a state Black Seal License (Boiler Operator - In Charge, what used to be called Fireman - In Charge) to be able to just steam it up (without using the steam, such as moving the loco). To be able to move it, you'd need a minimum Blue Seal Locomotive Engineer License. Boiler horsepower is another factor, if you own a big steam loco, you may need to upgrade to a Red Seal Engineer license.
Other states may require your insurance company to qualify you.
If you connect to outside lines, or cross public roadways and/or navigable waterways, you need federal qualifications and licensing.
If you run a landlocked diesel/gas unit, you probably won't need anything but the knowledge to run it.
With a couple of boiler failures over the last decade or so, live steamers and steam tractors have come under the scrutiny of the feds, calling them "antique and hobby boilers".
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