Until a few years ago, the money that immigrants sent back home every month was only their business. But remittances around the world now total more than $126 billion, according to the World Bank. So it's become an issue for economists, governments and politicians.

Pedro Amaya came to Virginia from El Salvador eight years ago. Like thousands of Hispanics in the U.S., Pedro and his four brothers work in construction. He lives with his wife and baby, and every month he sends money home to his parents in El Salvador. "Sometimes $300 per month, sometimes $200, they have another small income, but it is not enough for living. The economy in our country is not doing well."

Economic researchers say unskilled workers tend to send money back home more often and in small amounts. They are frequently illegal immigrants working for low wages, working in the service industries like tourism and restaurants.

Professionals and higher wage earners also send money but less often. The amounts they send are usually higher. The Ambassador of El Salvador in Washington, Rene Leon, admits sending money home. "Yes, I send remittances to El Salvador, I am part of those $2.5 billion in remittances."

The Ambassador says the $2.5 billion sent last year by two million Salvadorians in the U.S. represent more than 13 percent of the Gross Domestic Product of El Salvador.

Maria is from El Salvador and for years has been sending money to her parents and a daughter. She cleans hotels and cooks tamales at home for sale. She says sometimes she uses formal channels to send her money, like this office of Bancomercio in Washington. But most often she sends cash with friends traveling to El Salvador.

Legal channels for the international transfer of money charge 10 to 20 percent of the amount of money sent. It's a high price for the workers who also lose on non-favorable exchange rates.

None the less, the World Bank estimates that last year, remittances added up to approximately $126 billion. Dilip Ratha is a senior economist at the World Bank "Nobody knows how much money is actually going off in the form of cash or in informal transfers; whether it is through a friend or informal agencies, which are not registered at all, for example tour operators or export-import agencies."

Mexico, India and the Philippines receive the most in remittances. More than 60 percent of the Latino population in the U.S. is of Mexican descent. About Mexico Dr. Ratha says, "Mexico received $17 billion last year and that was higher than their foreign direct investment. It was about the same size as their oil exports."

The U.S. leads the world as a source of remittances to other countries. But Dr. Ratha estimates that most of the total migration and remittances happen between underdeveloped countries, in the southern hemisphere. For example those sent from South Africa to Sub Saharan Africa, or from Malaysia to South East Asia. About 80 percent of worldwide remittances are used for food, goods and services. Much of the rest goes into building better housing or buying properties.

Only a small portion is invested. Remittances have become a key element in some countries' fight against poverty -- both because of the money and the people who send it. Some even see it as a way out of poverty says Dr. Ratha. "Some countries have explicitly used migration as a development strategy."

Remittances come and go in all directions and it's become clear they are a new and important force in the global economy, propelled by an army of migrants around the world.