The <a href="https://en.wikipedia.org/wiki/National_Weather_Service" id="mwrg" rel="mw:WikiLink" title="National Weather Service">U.S. Weather Bureau</a> publish a paper which stated the width of a <a href="https://en.wikipedia.org/wiki/List_of_United_States_tornadoes_in_1946#April_21_event" id="mwrw" rel="mw:WikiLink" title="List of United States tornadoes in 1946">tornado</a> which struck the <a href="https://en.wikipedia.org/wiki/Timber_Lake,_South_Dakota" id="mwsA" rel="mw:WikiLink" title="Timber Lake, South Dakota">city of Timber Lake, South Dakota</a> was <span about="#mwt25" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"4"},"2":{"wt":"mi"},"3":{"wt":"km"}},"i":0}}]}' id="mwsQ" typeof="mw:Transclusion">4 miles (6.4</span><span about="#mwt25" typeof="mw:Entity"> </span><span about="#mwt25">km)</span>, which would make this the widest tornado ever documented in history.<sup about="#mwt29" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-4"}}' id="cite_ref-4" rel="dc:references" typeof="mw:Extension/ref"><a href="./April_21#cite_note-4" id="mwsg" style="counter-reset: mw-Ref 4;"><span class="mw-reflink-text" id="mwsw">[4]</span></a></sup>
<span class="mw-reference-text" id="mw-reference-text-cite_note-4"><cite about="#mwt26" class="citation journal cs1" id="mwBZY"><a class="external text" href="https://doi.org/10.1175%2F1520-0493%281946%29074%3C0073%3ASLSFA%3E2.0.CO%3B2" id="mwBZc" rel="mw:ExtLink nofollow">"Severe Local Storms for April 1946"</a>. <i id="mwBZg">Monthly Weather Review</i>. <b id="mwBZk">74</b> (4): 73. 1 April 1946. <a class="mw-redirect" href="./Bibcode_(identifier)" id="mwBZo" rel="mw:WikiLink" title="Bibcode (identifier)">Bibcode</a>:<a class="external text" href="https://ui.adsabs.harvard.edu/abs/1946MWRv...74...73." id="mwBZs" rel="mw:ExtLink nofollow">1946MWRv...74...73.</a>. <a class="mw-redirect" href="./Doi_(identifier)" id="mwBZw" rel="mw:WikiLink" title="Doi (identifier)">doi</a>:<span class="id-lock-free" id="mwBZ0" title="Freely accessible"><a class="external text" href="https://doi.org/10.1175%2F1520-0493%281946%29074%3C0073%3ASLSFA%3E2.0.CO%3B2" id="mwBZ4" rel="mw:ExtLink nofollow">10.1175/1520-0493(1946)074<span id="mwBZ8" typeof="mw:Entity">&lt;</span>0073:SLSFA<span id="mwBaA" typeof="mw:Entity">&gt;</span>2.0.CO<span id="mwBaE" typeof="mw:Entity">;</span>2</a></span>.</cite><span about="#mwt26" class="Z3988" id="mwBaI" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&amp;rft.genre=article&amp;rft.jtitle=Monthly+Weather+Review&amp;rft.atitle=Severe+Local+Storms+for+April+1946&amp;rft.volume=74&amp;rft.issue=4&amp;rft.pages=73&amp;rft.date=1946-04-01&amp;rft_id=info%3Adoi%2F10.1175%2F1520-0493%281946%29074%3C0073%3ASLSFA%3E2.0.CO%3B2&amp;rft_id=info%3Abibcode%2F1946MWRv...74...73.&amp;rft_id=https%3A%2F%2Fdoi.org%2F10.1175%252F1520-0493%25281946%2529074%253C0073%253ASLSFA%253E2.0.CO%253B2&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%3AApril+21"></span></span>