The wildcat notes issued by some Nebraska territorial banks caused considerable financial instability. The bills had insufficient backing and in some instances, no backing at all. Late in the summer of 1857, a financial panic in the East caused many of these banks to close their doors. A. G. Warner, in a historical paper read before the Nebraska State Historical Society in 1887, recalled the circumstances of the collapse of the Nemaha Valley Bank of Brownville in the fall of 1857 (Transactions and Reports, Vol. II, 1887):
"The Brownville Advertiser noted it as a misfortune that [Thomas L.] McKoy, the president of the bank, was absent in the east at the time of the crisis. This may have been a misfortune, but certainly it was not so for the gentleman himself. Nor did he hasten to get back with all the speed that had been expected of him. In fact he never came back at all . . . .
"[Alexander] Hallam, McKoy, and all that had been connected with the bank suddenly vanished. Advertisements failed to bring them to light, but each time as a given [legal] case was about to go against them by default, an attorney would put in an appearance, and spend his time making technical pleas designed to delay proceedings. Property was levied on that turned out to belong to other folks; a lot or two was sold. Finally in June, 1850 , Sheriff Plasters levied upon a safe, a table, a stove, and a letter-press, which altogether brought $63."
The writer of the above reminiscence remembered holding "one of the old worthless promises to pay up to the light, half expecting to find a watermark representing a wild cat rampant, but none was visible. The printer had done his utmost to make the bills valuable, and so well had he accomplished his purpose that long after the bank had failed, an enterprising citizen of Brownville took a pocketful of the currency down below St. Louis and passed it as good money."