The world's population is more mobile  today than ever before. In 2010, more than 200 million people left their home countries to live in a new country. This is about 3 percent of the total world population. Some experts believe that number will swell to 400 million by 2050. Rates of immigration have remained strong for the last 300 years, but patterns of immigration have changed since World War II. The backgrounds and experiences of today's immigrants are different from those of the typical European immigrant of the nineteenth and early twentieth centuries. Contemporary immigrants range from unskilled laborers to highly skilled professionals, and they come from and go to countries all over the world. In the nineteenth century and until World War II, immigration was primarily in one direction- from the Old World to the New World. This is no longer the case. Countries such as Russia and China, which have long been, and continue to be, significant source countries, are now also destination countries. There is also considerable mobility inside regions, such as from one European country to another, or among the countries of the former Soviet Union. In spite of such differences, the push and pull factors for immigration remain essentially the same as they were 100 years ago. Most people move to another country because they want a better life. For the majority of immigrants, this means better economic conditions. As in past generations, a labor shortage in one country often draws workers from another country, especially if wages are significantly higher. In some small countries, for example, Qatar, United Arab Emirates, and Kuwait, there are more jobs than citizens. The demand for labor is so high that the majority of the population consists of foreign-born workers, ranging from highly skilled engineers and financial experts to domestic and construction workers. In traditional destination countries, such as the United States, however, labor needs have changed. Today, although there is still demand for unskilled labor, there is increasing demand for people with a high level of skill and education. The need for less skilled labor has shifted to other countries. As work on farms and in industry in the United States and Canada once drew workers from all over the world, now work in factories in Taiwan and south Korea attracts workers from Vietnam, the Philippines, and Cambodia. Most global immigration is legal: however, a large number of people also move across national borders illegally in pursuit of employment. Experts estimate that about 15 to 20 percent of immigrants worldwide are in their new countries illegally. The United States has the largest number of these immigrants, followed by South Africa, with significant numbers also in Northern and Western Europe and Mexico. These immigrants face particular challenges because they often must hide from the authorities who might deport them back to their home countries. Their illegal status also means that employers may take advantage of them by forcing them to work longer hours and paying them less than the legal minimum wage. Although economics remains the most important motivation in all forms of immigrant, other factors are also important. Some people decide to leave their home countries because their actions or political beliefs make it dangerous for them to remain. Others choose to leave because their home country has become too dangerous and unstable, often because of war or political unrest. They wish to find a place that is secure for themselves and their families. Education is also a significant factor for many modern immigrants. They want to raise their children in a place where they can get a good education, which, in turn, they hope will provide them with better prospects for the future. Finally, family and community ties also play a role in immigration decisions. As in the past, once a group of people from one country establishes a community in a new country, more people from that country is likely to follow. The pattern, direction, and rate of immigration may change as the global economy changes. However, as long as life in a new country is more attractive than life in the old country, immigration will continue. Why do some employers sometimes pay illegal immigrants less than the legal minimum wage?
Employers know that they will not complain about their wages to authorities. They often do not speak good English. Authorities might send illegal immigrants back to their home country. Illegal workers often cause problems for employers.