Gender Imbalances and Labor Market Outcomes: Evidence from Large-Scale Mexican Migration

We examine the impact of a decline in the ratio of men to women on women's labor market outcomes. We do this for Mexico, where the sex and age imbalance of large-scale international migration has led to a significant decline in the male/female ratio. For example, according to Mexican census data, in the year 2000 the aggregate ratio of men to women 18–25 years old was 0.91, and for some states it was as low as 0.8. Given that the natural ratio of men to women is approximately 1:1 (Sen, 1990), this translates into 1–2 fewer men per 10 women than in contexts, such as in the United States or Brazil, with balanced sex ratios (see Figure 1).

Figure 1

The specific question we raise is whether the relative scarcity of men results in Mexican women entering high-skilled and better paying jobs over time. This question is relevant as there has been an increase in women's education and labor force participation across the developing world, but less evidence of improvements in the gender wage gap (Heath and Jayachandran, 2018; Deshpande et al., 2018; Lee and Wie, 2017; Yahmed, 2018). This suggests that the job quality for women has improved more slowly than education, and that occupational change may be key to understand if and when women's labor market outcomes and earnings improve. From an aggregate perspective these improvements are important given that higher female income may benefit the status, education, and health of both women and children, which in turn increases their country's development and growth (Duflo, 2012).

We focus on sex ratios as previous literature has found that declining number of men can affect women's schooling and the likelihood of employment, two precursors to changes in job type. In the context of the United States, Acemoglu et al. (2004) found that the large-scale deployment of men in the United States during World War II led to higher female labor force participation after the war, while Goldin (1991, 2006) documented the period as a tipping point with continued increases in the labor force participation of women later. Angrist (2002) found that decreases in the relative number of men among specific immigrant groups in the United States led to an increase in labor force participation among women in those same immigrant groups, while Mechoulan (2011) found that high incarceration rates for black men increase education and labor force participation rates for young, black women. More generally, Grossbard and Amuedo-Dorantes (2007) examined differences by region and age cohort due to baby booms and busts and found that lower sex ratios are associated with higher labor force participation rates for women.

There is less evidence on the impact of declining sex ratios on female labor market outcomes in developing countries, despite the fact that many of the drivers of changing sex ratios, such as international migration, wars, and violence, are more prevalent than in developed countries.

There is a literature on the impact on marriage, fertility, and bargaining power in the household.

We advance the current literature by providing more evidence of the impact of changes in sex ratios on women's labor market outcomes in a developing country setting and by examining impacts beyond labor force participation. To do this, we use Mexican census and inter-censal data from 1990 to 2015. We exploit variation across Mexican states and age groups, and start by documenting the dramatic decline in the sex ratios in Mexico, particularly for younger age groups. We also show that international migration is negatively and significantly related to the sex ratio, and explain a large portion in the variation across states.

In estimating the impact of declining sex ratios on women's labor market outcomes, our main empirical concern is over the endogeneity of sex ratio changes due to local labor demand shocks.

Here we differ from Raphael (2013) whose main concern is that women with particular marital and fertility preferences may move across states in response to the scarcity of men. He addressed this by using the relative supply of men in the state of birth as an instrument for the relative supply of men in the state of residence.

We find that declines in the relative number of men significantly improve women's labor market outcomes in Mexico. A one standard deviation decline in the sex ratio leads to 3–4 percentage points increase in women's labor force participation, 3–4 percentage points increase of the percentage of working women in white collar jobs, and 5–6 percentage points increase in the percentage in “brain”-intensive jobs. We also find that for some women average wages increase between 3% and 5%, while the female share in the top 25% of earners goes up by 1–2 percentage points. All these results constitute large changes relative to their respective means, and they are robust to different model specifications.

A driving force behind our results is likely human capital attainment. We end by exploring education as a key mechanism through which the absence of men could impact women's labor market outcomes. In the Mexican context high-skilled jobs do not require a college degree, as approximately 60% of white collar workers have an upper secondary education (12 years) or less.

See Table A1 in Appendix.

The rest of this article is structured as follows: Section 2 describes the main data sources and shows descriptive statistics; Section 3 discusses our empirical strategy; Section 4 presents the results; Section 5 explores education as a driving mechanism; and Section 6 provides some discussion and concludes.

The data on sex ratios and labor market outcomes come from the 1990, 2000, and 2010 Mexican Census and the 2015 Mexican Intercensal Survey, all accessed through IPUMS International (Minnesota Population Center 2020).

We do not use the 1995 Mexican population and dwelling counts, as there is no corresponding U.S. dataset in 1995 for our instrumental variable (the ACS began in 2001). Meanwhile the 2005 intercensal survey does not have information on hours, occupation, or income.

Panel A in Figure 1 shows the average sex ratios in Mexico for each of the years in our sample. The figure shows that similar to most countries, the sex ratio for younger age groups (ages 0–9) is over 1, reflecting the slightly higher natural number of male births. The sex ratio declines sharply in the 18–25 age group, where the ratio falls below 1 for all years. It remains below 1 for all remaining age groups and worsens over time for the older age groups. This shows that the problem of “absent men” became more, rather than less, acute over time. These results echo those of other papers, which find that Mexican migration is male dominated in all periods and has become increasingly male over time (Durand et al., 2001; Hanson and McIntosh, 2010; Raphael, 2013).

To show that the lower sex ratios in Mexico are distinctive, we compare them with those from the United States and Brazil using their respective Census data from IPUMS (Minnesota Population Center 2020). We choose Brazil because it is a Latin American country with similar income levels to Mexico. The results, presented in Panel B in Figure 1, confirm that Mexico's trajectory is unique. In the year 2000, in the United States the sex ratio for the 18–25 age group was 1.04, while that for Brazil it was 0.999. For Mexico the ratio was 0.9, which means that relative to the United States or Brazil there was one fewer man for every 10 women in that age group.

To estimate the effect of changes in the male–female sex ratio on female labor market outcomes, we use the following specification: (1) LM Outcomecst=β0+β1(MenWomen)cst+Xst'γ+δc+δt+δs+εcst {\rm{LM}}\,{\rm{Outcom}}{{\rm{e}}_{cst}} = {\beta _0} + {\beta _1}{\left( {{{{\rm{Men}}} \over {{\rm{Women}}}}} \right)_{cst}} + {X_{st}}'\gamma + {\delta _c} + {\delta _t} + {\delta _s} + {\varepsilon _{cst}}

The dependent variable are measures of labor market outcomes for women in an 8-year-age group c, in state s, and year t. This is modeled as a linear function of the sex ratio, state, year, and age group fixed effects, and industry controls (X_st), which are the percentage of the state's labor force by census year that is employed in each industry, as defined by two-digit codes. Standard errors are clustered at the state–age group level. If a decline in men relative to women led to increases in women entering the labor market and in certain high-skilled occupations, then we expect β₁ to be negative.

The main concern over the endogeneity of the sex ratio stems from local economic shocks, as negative shocks may incentivize men to leave seeking work elsewhere and may change labor market opportunities for women who remain.

For example, Hanson and Spilimbergo (1999) found that declines in Mexican wages are associated with increased Mexican migration, while Orrenius and Zavodny (2005) found that worse economic conditions in Mexico increase migration rates, particularly of lower skilled individuals. Meanwhile, Cerrutti and Massey (2001) found that Mexican men are significantly more likely to migrate for employment than women.

There also are concerns that the sex ratio could be influenced by women's re-location decisions, if for instance, women with characteristics that impact their labor market outcomes move to states with more (or less) favorable sex ratios. We therefore limit the sample to non-movers, defined as those who reside in their state of birth. This is the closest we can come to eliminating movers, as the census does not include location histories. We test the robustness of our results to this sample restriction in Table A3 in the Appendix.

One of the main channels through which the absence of men can impact women's labor market outcomes is through human capital accumulation. Human capital accumulation can interact or reinforce other mechanisms that may influence women's ability to get high-skilled and better paid jobs. For instance, as a result of fewer men, women may seek more schooling due to fewer marriage market opportunities (Raphael, 2013); an increase in time since women have less to do in the home (Goldin, 1991); an increase in remittances that provide resources to invest in education (Antman, 2015); and an increase in job vacancies for high-skilled jobs that motivate women to achieve the necessary level of schooling to fill-in these positions. While we cannot investigate each of these channels with our data, we can examine what happens to educational attainment as a result of missing men. We start with total years of schooling. The results shown in Table 4 indicate that a decline in the sex ratio of one standard deviation (approximately 0.05) leads to an increase in education of 0.6–0.9 years. Given that women get on average 8 years of education (less than lower secondary school), this constitutes an increase of 8–11%.

The next question is whether an increase in years of schooling falls at key points in the distribution that would push women into educational attainment levels deemed necessary for white collar jobs. To answer this, we examine three different attainment levels: a lower secondary education (9 years of schooling); an upper secondary education (12 years of schooling); or a college education (16 years of more). The results shown in Table 4 indicate that lower secondary school is a key point in the education distribution affected by declining sex ratios. A one standard deviation decrease in the sex ratio leads to an 8–13% increase in women with a lower secondary education. We also find an indication of some gains for college education, as all the coefficients are negative, but the results are not consistently statistically significant. Meanwhile we find positive coefficients at the upper secondary schooling level, meaning that declining sex ratios lowers the percentage of women with 12 years of schooling. This could be due to some women achieving more education by going on to college, or to some women achieving less education by stopping at lower secondary school. While we cannot rule out the possibility that some women are leaving school earlier to enter the labor market, the overall increase in years of schooling and the relative magnitude of the coefficients indicate that this is not likely the dominant story.

The results presented in Table 4 indicate that the education channel is operating most strongly on the marginal woman for whom finishing lower secondary school opens job opportunities. The stronger effect on this group is consistent with the average level of schooling for the men who are most likely to migrate. Furthermore, in this study the proportion of women with lower secondary schooling for the time period who have white collar jobs is non-negligible, reaching as much as 27.5%, as documented in Table A1 in the Appendix. These are likely the women who are driving the employment results.

We investigate if impact of declining sex ratios differs across those with more and less education. Results in Table 5 show that where we saw the most gains in schooling, the lower secondary level (panel C), women have increased their labor force participation and attained white collar and “brain” jobs, but have not increased their wages. This suggests that while these women are moving into high-skilled jobs, they are not moving into the best paid ones. Meanwhile, for college-educated women (panel A) we find evidence of an increase in high-skilled jobs and in wages. While the first stage is weak for this group (given this group is the least likely to migrate), these results suggest that the overall gains we see in terms of salary are driven by college-educated women. Finally, for women with more than lower secondary schooling but less than college (between 10 and 12 years), we find little evidence of movement into high-skilled jobs or an improvement in wages. Thus the aggregate gains appear to be driven by women at the lower and higher ends of the educational distribution for high-skilled jobs.

In this article, we explore the impact of declining ratios of men to women on the labor market outcomes of working age women in Mexico. Unlike other studies in Mexico, we explore outcomes beyond labor market participation, going further in the life cycle of women to look at job type, wages, and hours worked. We examine a more recent period in Mexico (1990–2015), when women's education and labor force participation have increased. These extensions shed light on factors that may change occupations for women, leading to better and higher paying jobs over time.

Overall we find that the decline in the relative number of men significantly improved labor market outcomes for women. We find that women are more likely to enter the labor force and are more likely to have high-skilled jobs once there. For women who achieve lower secondary schooling, we find that increased educational attainment may be a leading explanation for the job results seen. Interestingly, for this level of schooling we find no significant impacts on wages. This suggests that while these women move into high-skilled jobs, they may not be able to move into the highest paid ones. Meanwhile, the aggregate increase in wages that we find appears to be driven by college-educated women.

Despite gains in educational attainment and labor force participation, women have made muted improvements in job type or wages (Blau and Kahn, 2017, Heath and Jayachandran, 2018). Few studies in developing countries have found recent improvements in the gender wage gap (Ahmed and McGillivray, 2015). Recent literature has studied the role of gender norms as one potential explanation. Some of this work focuses on attitudes at the community level (Alesina et al., 2013; Fernández, 2013), while other has looked at intra-household dynamics (Bernhardt et al., 2018). Male migration in Mexico may have contributed to a break in those societal norms that defined the economic roles of women. Women may be observing high-skilled job opportunities becoming available and thus preparing themselves for these positions by seeking more education. Future research could explore whether the driving factor in the Mexican context was a change in social norms and exploit the reversal in migration trends to explore whether these changes are short-lived or long lasting.