The Notion Behind the Motion: Two Centuries of Emigration to the US
Historical migration rates to the United States provide an interesting window into the state of migration in the world today. The graph below (created using Google's MotionChart) offers rich information about the relationship between national income levels (GDP per capita) and rates of emigration from 62 countries of the world to the United States over the period 1820-2008. This is a complex figure, but it is the kind of bird's eye view that reveals otherwise invisible features of the world.
Tip: Press the Play button in the lower left side to watch migration data change over time, or use your mouse to drag the slider at the bottom of the chart to see the movement at a slower pace.
The vertical axis shows the total number of people who moved from each country to the U.S. during each decade, as a fraction of the origin-country population.¹ Scrolling forward along the time tracker to 1870, one recognizes, for example, that from 1870-1875, roughly 7.5% of Ireland moved to the United States. The horizontal axis records two main variables of interest. The first is GDP per capita in the sending country (measured in constant 1990 PPP dollars so as to be comparable across countries and over time). The second is the ratio of sending country GDP per capita to U.S. GDP per capita.
Tip: select "Sending Country GDP/U.S. GDP" from horizontal axis drop-down menu
In that same example of Ireland in 1870, Irish GDP per capita was $1,775. Lastly, note that the colors correspond to different geographic regions (unchanging over time), and the size of the respective (circle) observations are proportional to sending-country population in the given year. As a caveat, recognize that the use of GDP per capita clearly represents a rough approximation to the cross-country wage differences that remain the deep driver of international labor mobility.
Several important features of the world stand out in this figure:
· Migration can be large enough to help. Relative to the population of several Latin American and Caribbean countries, today's flows of Mexicans and Salvadorans -- for example -- to the U.S. are comparable to flows of people out of poor Europe in the 19th century. Giving many of their poorest people opportunities in America was an important part of the development strategies of Germany, Ireland, Italy, Sweden, Poland, Hungary, and many other countries. Similarly-sized flows from some of today's developing countries are not just feasible, but happening already.
· The poor are not poorer -- we're richer. Today's poor migrants are coming from places that, in real terms, are not poorer than the places that the United States' early migrants came from. In fact, real GDP per capita levels in several Latin American countries across the 20th century are similar if not greater to those in poor parts of Europe in the early-to-mid 19th century. But the American economy offers vastly more opportunities than it used to. At its peak, emigration from poor(er) Europe in the latter half of the 19th and early 20th century took place in countries whose economies were between half and three-quarters as productive as the U.S. economy. At comparable relative emigration rates, today's poor migrants are coming by and large from countries whose economies are between 1/20th and one quarter as productive as the U.S. economy today. If the U.S. was the land of opportunity for the huddled masses of Europe, it is a land of dramatically greater opportunity for today's poorest, because it has become far richer and stronger than it was then.
· But migration does not have to be large to have a large impact. Migration flows to the U.S. from India this century have only represented a miniscule fraction of India's population. But among that tiny trickle of people have been Indians who have helped build the exploding high-technology sector of India in hubs like Bengaluru, Hyderabad, and Mumbai. Of course it is infeasible for every Indian to have access to job opportunities in the United States, but mass migration is not at all necessary in order for migration to have a truly transformative impact on the development process. Circular migration has had profound impacts on the development of China, India, Taiwan, and Korea even through the movements of tiny fractions of the home-country population.
Sources
Sending country population and GDP per capita data was obtained from Maddison (2003). The decadal immigrant flows to the U.S. are recorded in the Department of Homeland Security's Yearbook of Immigration Statistics. We accessed the data from the 2006 Yearbook directly from the DHS website, accessed 25 AugU.S.t 2007. In particular, we U.S.ed the decadal data on immigrant flows from Table 2 "Persons Obtaining Legal Permanent Resident StatU.S. by Region and Selected Country of Last Residence: Fiscal Years 1820 to 2006." We then divided the relevant figures for the sending countries by their respective decade-average populations from Maddison (2003).
__________________________________________________________________________________________________________
¹The underlying data record migration rates, legal permanent residents as recorded in DHS Historical Immigration Statistics, over the decade (e.g. data for 1870 record the total number of migrants from 1870-1879; data for 2000 record total migrants from 2000-2009, where the latter two years are extrapolated forward). However, the Google gadget interpolates data points for individual years via arithmetic means, resulting in inter-decadal flows.