RESUMEN
This study examined the levels of substance use and changes across different migration stages, including pre-departure, travel, destination, and return, among Mexican migrants converging on the US-Mexico border. A cross-sectional survey was conducted in Tijuana, Mexico, between 2009 and 2010 among Mexican migrants returning from the US and those travelling from other Mexican regions. The overall prevalence of last 12-month at-risk drinking, illicit drug use, and current smoking, was 42.3, 17.7 and 31.4%, respectively. Compared to pre-departure migrants, males were at increased risk for illicit drug use at the destination and return stages. In contrast, females' alcohol consumption at the destination stage was lower than at pre-departure (p < 0.05). The level of smoking was stable across all stages for both genders. In the destination stage, undocumented migrants were more likely to use illicit drugs relative to their documented peers (p < 0.05). Binational interventions promoting substance use reduction are needed among this mobile population.