The <a href="https://en.wikipedia.org/wiki/Buenos_Aires_Underground" id="mwfQ" rel="mw:WikiLink" title="Buenos Aires Underground">Buenos Aires Metro</a>, the first underground railway system in the <a href="https://en.wikipedia.org/wiki/Southern_Hemisphere" id="mwfg" rel="mw:WikiLink" title="Southern Hemisphere">Southern Hemisphere</a> and in Latin America, begins operation.<sup about="#mwt50" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-9"}}' id="cite_ref-9" rel="dc:references" typeof="mw:Extension/ref"><a href="./December_1#cite_note-9" id="mwfw" style="counter-reset: mw-Ref 9;"><span class="mw-reflink-text" id="mwgA">[9]</span></a></sup>
<span class="mw-reference-text" id="mw-reference-text-cite_note-9"><a class="external text" href="http://blogs.lanacion.com.ar/historia-argentina/historia/el-primer-subte/" id="mwB_o" rel="mw:ExtLink nofollow">El primer subte</a> <a about="#mwt49" class="external text" data-mw='{"parts":[{"template":{"target":{"wt":"Webarchive","href":"./Template:Webarchive"},"params":{"url":{"wt":"https://web.archive.org/web/20150419212655/http://blogs.lanacion.com.ar/historia-argentina/historia/el-primer-subte/"},"date":{"wt":"2015-04-19"}},"i":0}}]}' href="https://web.archive.org/web/20150419212655/http://blogs.lanacion.com.ar/historia-argentina/historia/el-primer-subte/" id="mwB_s" rel="mw:ExtLink nofollow" typeof="mw:Transclusion">Archived</a><span about="#mwt49" id="mwB_w"> 2015-04-19 at the </span><a about="#mwt49" href="./Wayback_Machine" id="mwB_0" rel="mw:WikiLink" title="Wayback Machine">Wayback Machine</a> – <a href="./La_Nación" id="mwB_8" rel="mw:WikiLink" title="La Nación">La Nación</a>, 22 December 2010.</span>