Transatlantic migrations
Transatlantic migration refers to the movement of people across the Atlantic Ocean in order to settle on the continents of North and South America. It usually refers to migrations after Christopher Columbus' voyage to the Americas in 1492. For earlier Transatlantic crossings, see: Norse colonization of North America and Theory of Phoenician discovery of the Americas. 19th century onward. Among the various transatlantic migrations, the period of time between the mid-19th century to the early 20th century marks the “Age of Mass Migration” where 40% of U.S. population growth was due to the inflow of immigrants. Economic theory  sought to explain, however, if immigrants were positively or negatively selected from the sending pool into the United States. Ingrid Semmingsen in her book, "Norway to America: a History of the Migration", wrote “Many have asked if it was the more capable, the more enterprising and energetic persons who left, or if it was those who fell behind in the struggle for bread, the losers, the maladjusted, and the deviant” in reference to the composition of those who migrated into the United States. The Roy Model of comparative advantage suggests that where there are higher wages for skilled workers in  one location, the most able will migrate to that country and earn that income. Moreover, if there are higher wages for unskilled workers in one location, the least able will leave their own country and migrate to earn that income. As a result of the improvements in transportation after the Industrial Revolution, long-distance migrations increased in the 19th century. For example, the duration of the Atlantic passage fell from 5 weeks (1725) to one week (1900). In addition, the length of indentured servitude necessary to pay for the fare decreased from 4 years to approximately 4 weeks, substantially decreasing  one of the main deterrents for making the trek. Between 1846 and 1940, some 55 million migrants moved from Europe to America. 65% went to the United States. Other major receiving countries were Argentina, Canada, Brazil and Uruguay. Also, 2.5 million Asians migrated to the Americas, mostly to the Caribbean (where they worked as indentured servants in plantations) and some, notably the Japanese, to Brazil and the USA.