In the US, where movements of tired, poor and huddled masses are an intrinsic part of the national identity, the unprecedented mass exodus of people from their homes in the Gulf Region -- more than half a million refugees -- could unleash changes for years to come.
"I think we're looking at an event of enormous political and historical importance," said Steven Hahn, a University of Pennsylvania history professor who chronicled other mass movements in last year's Pulitzer Prize-winning book A Nation Under Our Feet: Black Political Struggles in the Rural South from Slavery to the Great Migration.
"We've never faced this type of relocation because of a natural disaster. It's likely to have an enormous impact on our entire country," he said.
While many expect New Orleans to rebuild, it's unlikely that everyone is eventually going to move back. Experts say there are lessons to be drawn from historic moves.
For example, "New Orleans-style" neighborhoods may develop in larger cities with restaurants, music and cultural aspects of home. Racial and social tensions may also emerge, as thousands of people move into less diverse neighborhoods.
"If you have mass numbers going to one place, you're going to have the same tensions you have with any immigrants," said Phillip Gay, sociology professor at San Diego State University. "But if you distribute them in smaller groups, there's a better chance they can settle."
In 1980, at least 125,000 Cubans came to Miami in boats. The resulting social service burden was enormous, and eventually federal government paid Florida US$370 million in emergency assistance to help defray the costs of such a large, irregular migration.
This week in Texas, authorities were soon overwhelmed by food stamp applications -- 26,000 in four days. Elsewhere in the country, communities taking in Gulf Coast evacuees by the thousands worried about taxing social programs that in many cases already were stretched thin.
To avoid that type of an impact, authorities in 1979 began dispersing a flow of 1.4 million Southeast Asian refugees to all 50 states.
The social experiment was only partially effective. Although some of those immigrants settled in their new homes, many more soon began a secondary migration to communities where their relatives were living, where the climates were warmer and where Asian-American populations were already in place.
When large numbers of people from one culture have moved -- by force or by choice -- into a new community, there is "real friction and real problems," said Robert Wheelersburg, an anthropology professor at Elizabethtown College in Pennsylvania.
This has happened before -- at the turn of the 20th century, when blacks moved North in search of jobs, riots broke out in cities like Springfield, Illinois.
While thousands are being welcomed with warm meals and new clothes around the country this week, Wheelersburg said it is only a matter of time before some tensions emerge.
"I think it could create some real cultural problems moving people to different parts of the country," he said. "New Orleans was very unique. There are many places that aren't so diverse."
The size of the migration forced by Katrina is mindboggling.
"There's just never been anything like this before, with so many displaced people, and they're going to be displaced for so long," said Judith Owens-Manley, director of community research at Hamilton College's Public Affairs Center in Clinton, New York.