http://cityroom.blogs.nytimes.com/20...enship-checks/

Can you be asked to demonstrate your citizenship or residency if you are riding on Amtrak or Greyhound inside the United States?

The answer, apparently, is yes — according to the United States government’s border and transportation officials.

But the frequency of this practice in New York State has raised protests from immigration advocates, who demonstrated in a march on Wednesday afternoon between Pennsylvania Station and Port Authority Bus Terminal.

It used to be a practice that was heard about only once in a while near upstate cities like Buffalo and Syracuse, said Maria Muentes, a spokeswoman with Families For Freedom, a group that helps people fight deportation. “Now we’re seeing it several times a week.”

The group had one instance in which a family was stopped and the mother detained on the train between New York and Chicago. “They should warn people that this could happen,” Ms. Muentes said.

Customs and Border Protection, a division of the Department of Homeland Security, said the stops are just part of routine practice that has gotten more frequent as the manpower on the Canadian border has increased. In the last few years, the number of agents along the northern border has tripled, according to Ramon Rivera, an agency spokesperson.