Organizers say the so-called National Day of Action for Immigration Justice will include
marches in more than 100 cities on Monday in a movement that is being compared to the civil rights marches of black Americans in the 1960's.
One of the first marches was held in the southern city of Atlanta where at least 30 thousand people formed a sea of white T-shirts as they walked the three kilometer route.
People marched in the small farming community of Garden City, Kansas, and events are planned in the nation's largest cities, like Los Angeles and Chicago, as well as those in between -- like Phoenix, Arizona.
Thousands are rallying in New York City, and a protest is taking place here in Washington at the foot of the Washington monument.
The marches are the latest in a series of protests against a House of Representatives proposal that would classify illegal immigrants as felons. The bill also would tighten border security and impose heavy fines on companies that employ illegal immigrants.
President Bush has welcomed Monday's protests. He says it is a sign that people feel strongly about the issue.
Mr. Bush told an audience of students in Washington that protests are a key way for people in a free society to express themselves.
He also called for compassion in the debate over proposed immigration reforms. He said people need to understand the United States is a nation of immigrants.
Critics say the House proposal is unfairly aimed at mostly Hispanic immigrants who enter the country to find jobs. They are calling on lawmakers to enact reforms that will give immigrants a path to citizenship and will ensure their civil rights.
Last week, the Senate failed to agree on a bill that would have created new citizenship measures for immigrants.
Republican Senator Arlen Specter said Sunday he expects legislators will hold new talks on the issue when they return in two weeks.