Lee’s Theory of Migration: Intervening Obstacles Model

Everett S. Lee’s Theory of Migration (1966) or Intervening Obstacles Model aimed to eliminate the shortcomings of the previous theories of migration by inculcating both opportunities and problems as factors of migration. Previously, most of the studies focused on making general unidimensional laws to explain migration e.g. Ravenstein’s Laws of Migration. However, none of these theories cared to touch upon the reasons of migration and socio-economic character of the migrants. Earlier theories of migration do not pay much attention to the migrants after the migrant has reached his/her destination. Therefore, Lee attempted to build a holistic theory of migration. In fact, Lee’s model is an upgrade of Theory of Intervening Opportunities by Stouffer.

Factors of Migration

According to Lee, there are four primary factors which determine the volume of migration and characteristics of migrants. These factors are as follows.

1. Factors at Place of Origin

  • The social and economic condition at the hometown of a migrant is very important in determining various aspects of migration i.e. volume, distance, term of stay at destination etc.
  • In Fig. 1, City-A is place of origin and have more push factors than the pull factors, therefore, people will emigrate from City-A.
  • For example, a war will push most of the people to emigrate from their hometown for a long time.
  • Similarly, the migration due to temporary economic recession is short term.

2. Factors at Destination

  • The social and economic condition of the destination is also very important.
  • Better education and work opportunities along with a good lifestyle attract more people whereas the overcrowding, pollution and low wages attract lesser people.
  • In Fig. 1, City-B is destination with more pull factors and little push factors, therefore people will immigrate to City-B.

3. Intervening Obstacle

  • Intervening obstacles refer to the problems and barriers which a migrant encounters while migrating from one place to another. For example, if a person wants to migrate from Mexico to U.S.A., he may encounter border police and get arrested. Likewise, if a young man wants to travel to England, he may have to clear IELTS exam for English proficiency which is not possible for all.
  • The intervening obstacles between place or origin and destination also control the volume and characteristics of migration.
  • The obstacles may be in the form of legal barriers, geographic barriers and political barriers (See Fig. 1).
  • For example, political animosity between India and Pakistan discourages migration between these two nations.

    Fig. 1: Push & Pull Factors and Intervening Obstacles

4. Personal Factors

  • These factors include religion, caste, class, income level, educational attainment, health, age, personal perception of a foreign country etc.
  • The personal factors determine the ability of a person to migrate. For instance, old people can not survive alone in a foreign nation whereas the young people can.
  • Similarly, income level determines the distance of migration i.e. local, national and international. In the case of India, only rich people migrate to western countries whereas the poor and middle class people only migrate to Southeast Asia or Arabian Peninsula.

The factors at place of origin and destination may be push factors (negative) and pull factors (positive). It is interplay between push and pull factors along with obstacles between place of origin and destination which determines volume of migration.

Lee’s Hypotheses of Migration

After analysis of these factors of migration, Lee propounded three sets of hypotheses as follows.

A) Regarding Volume of Migration

Volume of migration refers to the total number of people who have left their birthplace to reside in another area, temporarily or permanently.

  1. Diversity of an area encourages migration. New areas provide new opportunities and attract a greater number of immigrants. For example, lots of Europeans migrated to America during the colonial period for better opportunities. If conditions in various places are homogeneous, people are unlikely to migrate.
  2. Diversity of People increases the likelihood of people to migrate. Here, diversity of people refers to specialization of different ethnic groups in different occupations. Lee gives the example of colonial America where Greek chefs, German craftsmen, Jew traders and Irish labourers were in demand across the country. Therefore, they migrated to different parts of America due to demand for their special knowledge and work.  
  3. Intervening obstacles negatively affect the volume of migration. For instance, the U.S. banned the immigration from many countries during Trump’s presidency. Similarly, the Berlin wall hampered migration between East and West Germany.
  4. Business cycles affect the volume of migration differently during economic recession and expansion. During economic expansion, the businesses grow fast and recruit new workforce to ensure timely supply of goods. So, the immigration increases to the places of high economic growth. During recession, businesses lay-off workers and unemployment spreads, therefore, people emigrate from areas of economic recession.
  5. Volume and rate of migration increases between backward and developed regions with time. Such migration only stops when legal barriers are imposed. Otherwise, the destination becomes overcrowded.
  6. Development is positively related to volume of migration. Here, development refers to improvement in the educational level, industrial development, modes of transport and communication. Further, the development also reduces the impact of intervening obstacles on the volume of migration.

B) Regarding Streams of Migration

  1. Mostly, migration tends to take place within well defined streams. This means that people use pre-established routes and networks to migrate to specific destinations. For example, less educated Indians use the. Mexico border to enter the U.S. and then seek asylum. Similarly, early immigrants guide their brethren to follow their footsteps to better places.
  2. There is a counter-stream to every stream of migration. This means that some of the migrants return to their birthplace temporarily or permanently.
  3. Push factors at the places of origin of migrants are more successful for inducing emigration. This law denotes that the people generally avoid migration if their socio-economic condition is good at the place of origin despite availability of better life elsewhere. They migrate primarily because of exacerbation of socio-economic conditions at their birthplace e.g. war in Syria forced millions of people to migrate to Europe.
  4. If place of origin and destination are similar, the streams of migration become inefficient, therefore, equal number of people go to and from place of origin and destination.
  5. The migration stream is highly efficient if the intervening obstacles are great. This means that people will only bother to tackle great problems for migration to a specific destination when the reward is very high. For example, Indians and Pakistanis spend millions of Rupees and endanger their life in Mexico for reaching the U.S. because they earn very well in that country.
  6. Economic growth increases the efficiency of the migration stream and recession reduces it. The migrants benefit more at the destination during economic growth due to fast growth of industrial production and wages. Contrarily, recession raises unemployment and reduces wages of migrants.

C) Regarding Characteristics of Migrants

  1. Migration is selective. It means that push and pull factors only determine the volume and direction of flow. However, the individuals respond differently to these factors, therefore, the composition of migrants is not random but selective. For example in India, men tend to migrate for work to cities more than women due to patriarchal society. 
  2. Pull factors induce positive migration. This denotes the migration of people to afar places without any obligation or compulsion. Such migration takes place largely due better opportunities at destination not due to bad conditions at home. Such migrants are highly educated and professionals.
  3. Push factors induce negative migration. This denotes that the bad conditions at hometown forces the people to leave for better opportunities at other places. Therefore, the migrant group is not selective, instead a large chunk of population migrate from their birthplace.
  4. Push and pull factors operate together, therefore, migration tends to be bi-directional. People tend to arrive and depart to a given place due to various reasons. Take the example of a town with a large manufacturing base but having lack of educational facilities. Here, the college going age group will leave while the workers will arrive.
  5. Intervening obstacles filter-out the negative selective migrants. This means that the uneducated, economically weak or incapable people are not able to reach their destination due to various geographic, legal and political barriers.
  6. The propensity to migrate depends on the life cycle or age of the people. For instance, Indian women migrate to their in-laws’ homes after marriage. Similarly, students and workers have a higher propensity to migrate for better educational and work avenues.
  7. The characteristics of migrants depend on the culture of both the place of origin and destination. The migrants keep many cultural traits from their birthplace and learn new things from the destination.

Conclusion and Relevance

We can conclude that Lee’s theory of intervening obstacles is a comprehensive and exhaustive explanation of various aspects of migration e.g. volume of migration, streams of migration and characteristics of migrants. Lee accommodates almost all aspects of the process of migration and tries to explain them logically. Although it is an appreciable academic endeavor, Lee’s theory lacks objectivity. Therefore, applying this theory for policy formulation becomes tedious. For instance, the concept of diversity of area and people is abstract and vague in nature. Eventually, he formulated many hypotheses based on the experience of colonization of North America which is not applicable to most of the Asian countries. Nonetheless, this theory provides academic support for development of advanced theories of migration e.g. Mobility Transition Model by Wilbur Zelinsky.

Reference: Lee, Everett S., (1966), A Theory of Migration, Demography, Vol. 3, No. 1, pp 47-57.