I assume that you mean passenger services. At the national level, they are handled by Amtrak and locally by various transit authorities. Amtrak does not have an API as such, furthermore this is a discussion about cleaning the screen:
http://discuss.amtraktrains.com/index.php?/topic/32601-amtrakcom-api/
Mostly there are websites that do this, but they do this very rarely.
Transit authorities will have authority based on authority. There is no central clearinghouse like with the UK.
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