The New York Railroad Storm

What happened

A series of coronal mass ejections from a large, complex sunspot group triggered the most intense geomagnetic storm of the 20th century, with a peak Dst estimated around -907 nT. Geomagnetically induced currents caused telegraph and railroad-signal switchboards to catch fire in Brewster and Albany, New York, and disrupted the New York Central Railroad's entire signal and switching system below 125th Street. Aurora were reported as far south as Texas, Los Angeles, and Samoa.