migrants and the level of development of the place of origin, estimating differential earnings with natives. Using the Mexican Family Life Survey data, the author finds a negative effect on adult earnings associated with migrant human capital and her network, but no influence of the place of origin. However, none of these studies explore the differential wage gaps across gender due to internal migration.

# 4. Data

**In this study, multiple data sources are used.** The primary source of information is the latest Census of Population and Housing, which was conducted in March 2020. The Census allows for the identification of internal migrants during the period 2015-2020, and it also provides information on the reasons for migration. In addition, the study uses labor market indicators (such as unemployment, employment, and informality rates) coming from the National Labor Force Survey (ENOE), information on the incidence of crimes and perceptions of public security coming from the National Survey on Victimization and Perception of Public Safety (ENVIPE), information on experiences and perceptions of the population on public procedures and services coming from the National Survey on Governmental Quality and Impact (ENCIG), and information on past migration flows coming from the Intercensal Survey of 2015.

## 4.1. Measuring internal migration

**Internal migrants are identified using microdata from the latest Census of Population and Housing in México (Census of 2020).** The 2020 Census was carried out by the _Instituto Nacional de Estadística y Geografía_ (INEGI) from March 2 to 27. This dataset allows identifying internal migrants from 2015 to 2020, defined as those who resided in Mexico five years ago and moved to another state. This information is self-reported, answering the question, _“Five years ago, in March 2015, in which state of the Republic or in which country did (NAME) live?”_ While this question enables the identification of international migrants, the analysis is limited to internal migrants contrasted with non-internal migrants, identified as those who resided in Mexico five years ago and stayed in the same state.

**Using Census data to identify internal migrants in Mexico has some limitations.** The question that allows identifying internal migrants has the inevitable shortcoming that any 2-stage-migration during the five years is considered as a one-stage migration. Moreover, any intermediate migration within the five years cannot be identified. Therefore, the analysis of internal migration in this study considers as “permanent” any migration decision from the original state of residence.

**Additionally, the questionnaire elicits information about the personal reasons for migration** . This data is an essential input for the analysis since it allows a better understanding of the internal migration patterns and the identification of heterogeneous migration decisions among women and men. However, the units of analysis are limited to the individual and dwelling levels. This fact leaves aside the possibility of analyses at the household level.

**Around 3.4 percent of the population residing in Mexico in 2015 moved to another state during the period 2015-2020.** In 2020, 91.4 percent of the people living in Mexico resided in the country five years ago (in March 2015). Of these, 3.4 percent migrated from another state between 2015 and 2020, representing nearly four million people. The internal migration rate is higher among men than women (3.6 against 3.3 percent). However, women represented almost half (49.8 percent) of the total internal migrants in 2020 (Figure 4).

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