14. Mustang — Do you know where Mustangs came from? The first mustangs descended from Spanish horses brought to Mexico in the 1500's by the Conquistadors. Some of these horses escaped and quickly spread throughout western North America. As early as 1900, 2 million horses roamed wild in North America. Today, less than 30,000 are allowed by federal law to occupy public lands. In 1971, the US Congress recognized Mustangs as “living symbols of the historic and pioneer spirit of the West, which continue to contribute to the diversity of life forms within the Nation and enrich the lives of the American people.”