This study examined differences in mother-reported physical activity (PA) and screen time (ST) based on child sex and mothers’ perceptions of PA resources for Mexican-heritage (MH) children residing in Texas-Mexico border colonias. Mothers with children 8 to 10 years old (n = 335) from colonias in south Texas reported if there were places for their child to be physically active and their child’s hours of PA and ST per day during the week and weekend. Two-way ANCOVAs examined differences in child PA and ST based on presence of PA places and child sex. Only 46.0% of mothers (n = 159) reported places for their child to be physically active; with no significant difference based on sex. Mothers’ perceptions of a place to play was differentially beneficial for girls’ weekday PA and ST. Findings suggest a need to increase perceived and/or actual access to PA places in colonias communities, particularly for girls.