1914, after the duche of Austria is shot dead in Serbia. That ignited 1st world war, but did not cause world war 1.
The main cause of world war 1 is for secret alliance formed between nations. When Austria declare war on Serbia, Russia comes in to side with Serbia, then Germany joins Austria, and so on. It became a big mess that was never intended that way.
Answer: Researchers estimate that there were 15 million to 20 million American Indians in the territory that would become the United States at the time of first contact with European explorers in the 15th century.
