Natural increase has essentially stopped. Immigration helps but there are probably not going to be enough immigrants to keep growing for much longer unless the

Natural increase has essentially stopped. Immigration helps but there are probably not going to be enough immigrants to keep growing for much longer unless the US starts allowing Canada-level immigration (see that growth curve steadily decreasing). It will take a while though, probably another 40 years or so until the US sees declines, but growth rates will collapse in the coming decades unless demographic trends change.