This article analyzes the effects of the Mexico-United States geopolitical border in social and cultural differentiation, using the crossing experience as the analytical core. Based in 60 life histories of residents of the Mexico-USA border region, a typology of life experiences structured around border crossing is developed, including a wide range of life experiences, from those that involve never having crossed the border to those that are precisely the product of border crossing. The experienced border encompasses the subjectified experience of the region, integrating both the meaning of crossing and the structural elements that historically have defined the border: proximity, asymmetry, and interaction.