Mexican immigrants living in the United States sent $7 billion back to their families in Mexico last year. Salvadoran immigrants will send back $2 billion this year. Instead of severing ties to their native lands to seek their fortunes in a new country, U.S. immigrants are increasingly living in both worlds.

American University history professor Alan Kraut says the speed of transportation and communication today enables immigrants to maintain close ties to their native lands. But he adds the transnational trend has historical precedent. "Whole towns in southern Italy in the early 20th century owed their economies to the moneys that were being sent home by migrants [in the U.S.] to their wives and their parents," he notes. "This is not something that is really new."

But Wellesley College Professor Peggy Levitt, author of a new book entitled "The Transnational Villagers," insists technology has made the experience of today's immigrants very different.

When you can telephone your children in the Dominican Republic from Boston each night and help them with their homework, Peggy Levitt says, you are living in two countries, not one. "The way that people stay connected to their sending communities now is much more intense and much more frequent and much more widespread than it was in the past," she says. "It goes against our assumptions that they trade one allegiance for the other."

Alan Kraut sees nothing wrong with such dual national identities. "The fear of many anti-immigrant forces is that somehow this kind of transnationalism will create a disloyalty to the country," he says. "I do not think that is the case."

But Peggy Levitt is more concerned about the economic consequences than the political ones. Conditions in the immigrant's countries of origin may deteriorate. "As you depend more and more on remittances," she says, "the economic bases of these [sending country] communities weaken, and it gets the sending country government off the hook, because they are able to pursue policies that made people have to emigrate to begin with, because they could not support their families with the economic opportunities that were available."

As for the U.S. immigrants, Ms. Levitt says, many are forced to work two and three jobs to earn the money to support loved ones in two countries. For many of these people, she says, living in two countries means no life at all.