* ''None yet'May 14–15''': The major May 1921 geomagnetic storm occurs. <br> The three-day storm was caused by the impact of an extraordinarily powerful coronal mass ejection on [[Earth]]'s magnetosphere. It was the most intense geomagnetic storm of the [[20th century]]. <br> The storm's electrical current sparked a number of fires worldwide, and was extensively reported in New York City, which was a center of telegraph activity as a railroad hub. * Adolf Hitler becomes Führer of the Nazi Party in [[Germany]].