I lived for 35 years near Havre de Grace, Maryland on the Chesapeake Bay at the mouth of the Susquehanna River.  The Susquehanna River delta (flats) was, in earlier times, the duck and goose hunting capital of the east.  For many years commercial hunting of ducks and geese on the flats supplied Baltimore, Washington, Philadelphia, and New York with wild game for the table.  Decoy carvers in Havre de Grace and the other towns around the bay supplied hand-carved decoys for the many waterfowl hunters.  In the early 1900's the federal government began to get involved in wildlife conservation and in 1918 The Migratory Bird Treaty between the U.S. and Canada became effective.  This treaty put an end to commercial waterfowl hunting in the U.S. and Canada.  Professional hunters and decoy makers were forced to turn to other sources to make a living.  Many of these men became sport-hunting guides.  Others found they could make small decoys and sell them as souvenirs or give them to their children as toys.  Contests and shows of decorative bird carvings slowly advanced decoy carving to an art form unique to America.  What started as a conservation measure effectively stopped a major industry and led to the creation of an art form.