Answer:
Mostly natural resources.
Step-by-step explanation:
The Americas were rumored to have a lot of gold. The gold as well as other products produced in the Americas intrigued the Spanish and British. The Spanish had another reason though: The spread of Christianity. They also wanted more land to settle, and Spain, who didn't have much of an Empire at the time, wanted to be a major power, competiting with the British. The main conflict, though, came after France decided to settle in North America as well, however they took over most of Canada, and didn't have as much of a stake in the US.