A reduction in US population growth would significantly reduce world resource consumption. If we are concerned about the welfare of our children and the future of the economy, then we should slow and stop our population growth now. Cities are no longer just expanding skyward. Instead, subdivisions and skyscrapers encroach upon arable farmland. Eventually the remaining farmland will no longer support food consumption needs.
More population also means more waste.
There is continually less space for landfills, and more population means more stress on waste disposal. No one wants a landfill in his or her backyard. To protect our habitat for future generations, we must care for it today. In the end, larger populations will cause more stress on the land. However, simply eliminating immigration will not solve all our problems.