  On March 4, 2009, the DZero and CDF collaborations at Fermilab's Tevatron
Collider submitted papers to Physical Review Letters announcing observation of
single top quark production. This review paper describes the successful
searches carried out independently by the two collaborations, allowing the
reader to see the similarities and differences that led to the simultaneous
discoveries. Both collaborations measured a cross section
sigma(ppbar->tb+X,tqb+X) consistent with the standard model prediction at 5.0
standard deviation significance, and set a lower limit on the quark mixing
matrix element |V_tb| without assuming matrix unitarity with three quark
generations.
