There are a couple of options for traveling between New York City and Montreal by Amtrak train or Greyhound bus.
Travel by Amtrak Train
Amtrak is the train company in the USA. There is a line that runs between New York City and Montreal. The trip generally takes about 11 hours. A search today found one-way fares from New York City to Montreal starting at $62 (current prices may be different). The train is generally more comfortable than the bus.
For Amtrak train schedule and fare information, please visit www.amtrak.com.
Travel by Greyhound Bus
There is also a Greyhound Bus line that runs between New York City and Montreal. The Bus generally takes about 8 or 9 hours, and a quick search today showed one-way fares at $84 (current prices may be different).
For Greyhound bus schedules and fare information, please visit www.greyhound.com.