There are more than 20,000 polar bears living in the wild in the world, with a relatively stable population.In an effort to protect them, the United States passed a law in 1972 banning the hunting of polar bears except for their survival.In 1973, the Arctic nations of the United States, Canada, Norway, Denmark and the former Soviet Union signed an international treaty to protect polar bears. In addition to limiting hunting and trade, the treaty also included provisions to protect the bears' habitat and cooperate in research.