Just north of the line dividing the United States and Mexico, the US government is planning the construction of its newest border facility in San Ysidro, California. The development of this station (and other stations currently in planning) is reconstituting the identity of the border, from a definitive line of separation, to the implementation of an expanded zone of control and security, at once amorphous, occupiable, and ultimately more defensible. These new qualities necessarily recalibrate many of the roles historically played by the border crossing whose iconography and form, coming from movement, arrival, and passage, have produced some of our most significant and important structures.In particular, the border shared by Mexico and the United States is a most compelling area to examine issues present in a complex and evolving relationship between these countries and the regions they represent. The border station provides a context to examine the history and current state of these highly interwoven relationships, and by extension, relationships beyond this specific context. Freedom of movement has been a fundamental component of the identity of the United States, both within its national consciousness, as well as to those outside its borders. Here, the aspirational aspects of free movement, as well as the increasingly intense desire to control it, are inherent issues that the design might explore.While the cultural and political context of this project is one trajectory of exploration, the resolution of complex and seemingly \’pragmatic\’ design criteria is also ground for significant invention. An extreme and complex set of scales and types of movements must be accommodated by the architecture of the border station in, balancing, strategizing, or amplifying multiple types of experience occurring simultaneously.A border crossing has the potential to be an occasion of significant symbolic importance, generating a wide range of emotions from optimism and anticipation, to fear and suspicion; but it is also a constant and more prosaic daily event for many, and a working component of \”legitimate and illegitimate\” international trade and commerce. From the fastest to the most plodding conveyance, a breadth of temporal scales is present. Each of these experiences, whether the norm or the exceptional, must be considered in a finely balanced and meaningful choreography.