Massey et al, An Evaluation...

Douglas S. Massey et al (1994)
“An Evaluation of International Migration Theory: The North American Case”

This essay is basically a literature review. The main point can be summarized quite briefly: existing evidence about migration from Central America and the Caribbean to the US confirms each and every one of the theories of migration reviewed in Massey et al’s previous article. As the authors put it, “each model received at least some empirical support, suggesting that each theory captures an element of truth.” The main problem is that some of the theories have not been subject to much testing.

For the authors’ synthesized “story” of migration, see pp. 740-741.

Neoclassical economics
The effects of wage differentials between the sending and receiving country on migration have been extensively studied, especially in the cases of Mexico and Puerto Rico. The general finding is that relative wages are a significant predictor of migration. However, they only explain part of the variance. Further, employment differentials are often more significant than wage differentials.

New economics of migration
Evidence from Mexico supports the tenets of the new economics. Remittances from migrants to the US are often used for investment, suggesting that migration is a way to circumvent imperfect credit markets and to manage risk. Also, relative deprivation is found to be a significant predictor of migration abroad (but not internal migration).

Segmented labor market theory
Studies show that migrants usually wind up in the secondary sector, as segmented labor market theory predicts. In cities with large immigrant populations there is a third sector: the ethnic enclave, where workers can earn greater returns to skill and experience than in the secondary sector. (The big winners in the enclave economy, however, are the entrepreneurs.) Mexican farm labor cannot be regarded as an ethnic enclave because the workers are merely exploited.
Contrary to the predictions of segmented labor market theory, the demand for low-wage labor in receiving countries is usually found to have less explanatory power than conditions in the sending country.

World systems theory
A number of the predictions of world systems theory are confirmed by evidence.

Industrialization and agricultural development often initiate migratory flows.
Migration tends to flow towards the global cities in the US. In the global cities, the employment structure is bifurcating into low-wage and high-wage service sectors. Blue-collar jobs are relocating to smaller population centers.
Migration also tends to follow US military and foreign policy commitments, suggesting that these build links between the US and developing nations.

Network theory
Network effects on migration have been extensively confirmed by a variety of evidence.
Immigrant multiplier effect: since the US gives preference to the family members of existing residents, each new immigrant pulls a certain number of additional immigrants afterward.

Cumulative causation: how do migration incentives change over time?

The theory that past migration experience increases the probability of migrating again is confirmed by data.
While the data supports the importance of networks in causing migration, there is insufficient evidence about how networks change over time.
Data shows that migration increases relative deprivation in sending communities, thereby increasing the incentives for migration. The effects of remittances on relative deprivation are exacerbated when the remittances are used for income-producing investments.
Some hypothesize that migration increases the concentration of landholding in sending communities, which further increases the incentives to migrate. This has not yet been proved.
Some hypothesize that migration leads to a “culture of migration”, encouraging further migration in the future. This assertion is hard to prove, but anecdotal evidence supports it.