The United States, has a very high national debt, that has been growing at an extremely high pace in the 21st century; in addition, the aggregate personal debt of America's citizens are at record highs, with all this having occurred, during what is considered to be a nearly ten year economic expansion. Not only is the current national debt very high, the servicing of that interest rate for that debt, is now, after nearly a decade, inexorably climbing as the Federal Reserve has begun the process of normalizing interest rates. None of this bodes well for America, especially since it cannot and has not been able to grow its GDP at even a 3% or better rate, since 2005.
While there are many avenues to possibly escape or to alleviate such high debt loads, by far, the best of them all is to increase GDP and our productivity levels so as to literally through the growth of the economy, outrun and thereby begin to pay down the debt load so heavily hanging upon America. For instance, India and China, the two most populous nations in the world, have been able to grow their GDP at rates of 7% or higher over the last decade, which, admittedly, they have been able to accomplish from a far lower GDP base to begin with, yet, it still indicates that such economic growth is achievable.
The upshot is that without appreciably higher American economic growth, than there are not a lot of ways, that won't involve austerity, discipline, or a meaningful increase in taxes, that will be able to make a dent into our debt, other than a much higher productive growth rate. The best way to augment such a growth rate is to increase immigration substantially, especially with immigrants that are young and motivated, not only because the present population hasn't been able to do much of anything, but also because younger people are often the engines of economic growth, because they are driven to apply themselves so as to earn good money, and eagerly will spend that money, rightfully enjoying the fruits of their hard labor.
Fortunately, for America, the country has the land, infrastructure, food, energy, and educational facilities, along with the reputation of being the land of the free as well as the land of opportunity; so that, America is indeed a highly desirable place to immigrate to for many millions of people, of which, America in order to kick start its economic growth rate should make it a point to encourage such immigration, or else it will eventually find that it can no longer kick the can down the road, in regards to its monstrous debt load.
The bottom line is that our present day economic growth is too low, along with our national debt getting appreciably worse by the minute, so that, America needs to take a page from yesteryear, when immigrants were welcomed because they were an integral part of our westward expansion and our Manifest Destiny. The real driving force that encourages higher growth is that desire for liberty, the good life, and the pursuit of happiness, especially from those that hunger greatly and yearn to breathe free upon our shores.