requirement to back up the currency with treasuries. When the treasuries fluctuated in value, banks had to recall loans or borrow from other banks or clearinghouses. The second problem was that the system created seasonal liquidity spikes. A rural bank had deposit accounts at a larger bank, that it withdrew from when the need for funds was highest, e.g., in the planting season. When combined liquidity demands were too big, the bank again had to find a lender of last resort. These liquidity crises led to bank runs, causing severe disruptions and depressions, the worst of which was the Panic of 1907. National banks issued National Bank Notes as currency. Because they were uniformly backed by US government debt, they generally traded at comparable values in contrast to the notes issued during the Free Banking era in which notes from different banks could have significantly different values. National bank notes were not however "lawful tender", and could not be used as bank reserves under the National Bank Act. The Federal government issued greenbacks which fulfilled this role along with gold. Congress suspended the gold standard in 1861 early in the Civil War and began issuing paper currency (greenbacks). The federally issued greenbacks were gradually supposed to be eliminated in favor of national bank notes after the Specie Payment Resumption Act of 1875 was passed. However, the elimination of the greenbacks was suspended in 1878 and the notes remained in circulation. Federal debt throughout the period continued to be paid in gold. In 1879, the United States had returned to the gold standard, and all currency could be redeemed in gold. 1907–1913: Creation of the Federal Reserve System Panic of 1907 alarms bankers Early in 1907, New York Times Annual Financial Review published Paul Warburg's (a partner of Kuhn, Loeb and Co.) first official reform plan, entitled "A Plan for a Modified Central Bank", in which he outlined remedies that he thought might avert panics. Early in 1907, Jacob Schiff, the chief executive officer of Kuhn, Loeb and Co., in a speech to the New York Chamber of Commerce, warned that "unless we have a central bank with adequate control of credit resources, this country is going to undergo the most severe and far reaching money panic in its history." "The Panic of 1907" hit full stride in October. [Herrick] Bankers felt the real problem was that the United States was