Answer:
The U.S. was going through great industrial growth. There were many technological developments that cheapened and increased the production of goods. These goods required source material to be made and consumer markets to be sold to.
Step-by-step explanation:
China was an important economic goal for the U.S. in the late 1800s because it had a huge consumer market. Americans back then wanted to sell their many goods to the Chinese.
Another goal of imperialism, as it always is in capitalism, was to make production cheaper. And it was cheaper to produce some goods outside the country, like the sugar that was cheaper when produced in Hawaii by Chinese, Japanese, Filipino, and native workers. That's why Hawaii was annexed in 1898.
The peak of American imperialism was the Spanish-American-Cuban-Filipino war in 1898. It was economically motivated and granted American good's access to Chinese and Latin America markets.