Explain why the United States needed to expand its trade into new markets

For resources.

Explanation:

Resources is power, so in order to achieve a power Nation, we need to expand and make act of presence in other markets. With this we will be able to benefit for the resources that other lands have. It's most likely the empire centuries ago. Their expansion was always motivated for power and money.

We need to expand trade into new markets so we can get goods and other foreign things to benefit our country