Ne of the factors that promoted america's search for new markets between 1865 and 1900 was

One of the factors that promoted America's search for new markets between 1865 and 1900 was industrial and agricultural overproduction.

At the time, America was producing a lot - however, there weren't enough people in the country to buy that much goods. This is why it had to spread to other countries and their markets as well - in order to reach a larger customer base.