<a href="https://en.wikipedia.org/wiki/Gadsden_Purchase" id="mwTw" rel="mw:WikiLink" title="Gadsden Purchase">Gadsden Purchase</a>: The United States buys land from Mexico to facilitate <a href="https://en.wikipedia.org/wiki/Rail_transport" id="mwUA" rel="mw:WikiLink" title="Rail transport">railroad</a> building in the <a href="https://en.wikipedia.org/wiki/Southwestern_United_States" id="mwUQ" rel="mw:WikiLink" title="Southwestern United States">Southwest</a>.