Seward's Folly - the check was good
Earlier this year was the 140th anniversary of the Alaska Purchase.
March 30, 1867
Treaty concerning the Cession of the Russian Possessions in North America by his Majesty the Emperor of all the Russias to the United States of America; Concluded March 30, 1867; Ratified by the United States May 28, 1867; Exchanged June 20, 1867; Proclaimed by the United States June 20, 1867.
Map from the Alaska State Library.
Apparently the check was good. Here is the actual cancelled check for the purchase of Alaska (from World Book Online):