During the Great Depression, one third of all banks in the United States failed. Scholars dispute reason for their demise. This essay analyzes new evidence on the sources of bank distress. The data demonstrates that contagion via correspondent networks and bank runs propagated the initial banking panics in the fall of 1930. As the depression deepened and asset values declined, insolvency loomed as the principal threat to depository institutions. These patterns corroborate some and question other conjectures concerning the causes and consequences of the financial crisis during the Great Contraction.