What’s the law against train horns? Is it illegal to blow them in town or what?
Just dont honk where you live lol
What state you live in?
Important question, but also know ordinances will vary from town to town, city to city, county to county. Know what they are, and be aware of the consequences you could possibly face if you happened to get into trouble. This is part of being responsible with your horns, as there will always be someone…somewhere, that thinks that you honking your horns to scare people should be punishable as if you were to have discharged a firearm at them. Crazy, but it happens. 
There are some crazy areas, like most of CA…that can/and will seize your vehicle for simple violations like this. Just know what you have the chance of facing, before the reality itself bites you. CYA.
Texas, midland county, midland texas
Just be CAREFUL where you honk those! here in California its an infraction “Horn on vehicle makes to loud, harsh or unnecessary noise.” I sounded mine right in front of 5 cops during cruise night but they really didn’t do anything. Its all about timing and knowing when and where to honk.
where in cali is this? I have sounded mine if front of 5 cops during a parade I was in but they didn’t do anything. btw I am on the central coast. smack in between LA and SF.
In Florida it falls under the noise ordnance (the same as playing your stereo too loud) but it must have a separate button than your regular horn. As long as your in an area that doesn’t have a noise ordnance blow to your harts content 