DOL, found that, of married farmworkers, sixty-seven percent of Mexican males immigrated to the United States before their wives.
When married Mexican farmworkers decide to emigrate to the US, the males usually come alone first. 
mnli hypothesis: When married Mexican farmworkers decide to emigrate to the US, the males usually come alone first.  premise: DOL, found that, of married farmworkers, sixty-seven percent of Mexican males immigrated to the United States before their wives.