Why would a fall in U.S. interest rates cause a decrease in the value of the dollar? As interest rates decrease, foreigners invest more in the United States, which will raise prices and increase the value of the dollar. When interest rates decrease, foreigners invest less in the United States, which will decrease the demand for the dollar. When interest rates decrease, foreigners invest less in the United States, which will increase the demand for the dollar. As interest rates decrease, foreigners invest more in the United States, which will decrease the demand for the dollar