Can countries such as the US continue to grow?

It is possible for countries such as the US to continue to increase in population and/or in Gross Domestic Product; they can also grow in a geographic sense by annexing other countries (no nation in the Western Hemisphere could defeat the US if it were to invade, for example). If we are to engage in flights of imagination, it is not impossible in theory that the US will colonize the moon, Mars, the asteroid belt, etc., and expand into outer space, which offers tremendously more resources than those of the planet Earth, although in all honesty I do not expect this to actually happen. And for nations that remain limited by the planet Earth, there is only so much room, and so many resources, and eventually it is impossible to grow any further. The planet Earth presently has a population of about seven billion people, many of whom do not eat well. If the population were to increase to twenty billion, I guarantee that there would be mass starvation. There is only so much food that the planet can produce. Growth does not continue indefinitely.