Over the past four centuries, the United States has undergone a dramatic transformation, with vast stretches of forestland giving way to agriculture, urban development, and industry. Once covering a significant portion of the country, forests have been steadily shrinking since the 1600s as human settlement expanded westward. New research by Earth System Science Data reveals the extent of this decline, showing how once-dense woodlands have been replaced by croplands, pastures, and sprawling cities. The research comes as Donald Trump signed a new executive order this month to decrease U.S. reliance on foreign lumber. The order could result in the felling of millions of trees in the U.S. …Since the early 1600s, the U.S. has experienced a net loss of approximately 258 million acres of forest. …To replace the volume of lumber imported from Canada, about 17 million mature pine trees—each 80 feet tall and with a 2-foot diameter—would need to be harvested from U.S. forests.