21.6 + 16.6) more than men working outside the _maquila_ sector and 38 percent (≈ 28.7 + 9.5) more than women working outside the sector (table 7).<sup>11</sup>

**Table 7 Wage Premium Results from Specification (2) (percent)**

|_Item_|Maquila|_Non-maquila_|
|---|---|---|
|Men|2<br>δ = 21.5|Control|
|Women|= 9.5<br>3<br>2<br>1<br>δ<br>δ<br>δ<br>+<br>+|1<br>δ<br>= -28.7|
|Wage gap (men/women)|= 12<br>3<br>1<br>)<br>(<br>δ<br>δ +<br>−|1<br>δ<br>−<br>= 28.7|

_Source_ : Authors’ estimates. Note: All the parameters are significant at the 1 percent level.

The results for specification 2 reveal another important feature of the _maquila_ sector: the fact that the gender wage gap is 16.6 percentage points smaller than the gap observed in industries outside the sector. For this reason, the increase in the importance of the _maquila_ industry in total employment had a gender-equalizing effect.

The wage premia shown in table 7 are the average over the entire period of analysis; these estimates do not consider any time dimension, as observations from the four household surveys are pooled in a single sample. One of the hypotheses outlined earlier was that the _maquila_ boom of the 1990s resulted in a growing wage premium for workers in the sector. To test this hypothesis, we formulate specification (3a) in table 6, which allows for dynamic effects (the wage premia related to gender, the _maquila_ sector, and the interaction between this two can take different values over time). All the time-interacting terms, or difference-in-difference (DID) estimators, take 1991 as the base year, capturing the change in the parameter over time with respect to the initial year. Consider first the DID estimator for the premium received by workers in _maquila_ . The lack of statistical significance for this estimator indicates that the _maquila_ premium remained constant during the time period analyzed here, except in 1995. This is not the case for the gender wage gap, which decreased over time (significantly so in 2001 and 2006). The reduction in the gender wage gap outside the _maquila_ sector partly explains the lack of significant dynamic effects on wage premia for women working in _maquila_ . In fact, the DID estimator on the interactive term is negative and significant in 2006, implying that women did not receive an extra wage premium for working in the _maquila_ sector in 2006 (that is, the gender wage gap was the same in and out of the _maquila_ sector).

The lack of significant dynamic effects deserves some explanation. Although the results on _maquila_ wage premia suggest some level of labor market segmentation, a minimum degree of labor mobility would be enough to offset any long-term trend in wage differentials between the _maquila_ and other sectors. As shown by the identical specifications (3a) and (3b), _maquila_ workers earned wages that were about 24 percent higher than workers outside the sector in all

> 11. Consider the case of a woman employed outside the _maquila_ sector. According to specification 2 of table 6, she earns 28.7 percent less than. Because she is not working in the _maquila_ sector, she does not benefit from the 9.5 percent premium that women in the sector enjoy. Therefore, on average a woman employed outside the sector earns 38 percent less than a woman employed in the sector.

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