&gt; You&#x27;ve never seen the ag inspection stations at California border crossings, or the Border Patrol posts near the NM&#x2F;TX line?<p>The latter has nothing essential to do with the NM&#x2F;TX border, there are border patrol checkpoints (including mobile ones) in a pretty wide swath &quot;near&quot; the Mexican border. They don&#x27;t exist to enforce any kind of control on <i>state</i> borders.