None of the 4 major political parties is properly addressing the overpopulation problem. The Democrats, Libertarians, and Greens are all in favor of open borders. They advocate allowing unlimited numbers of people to enter the country to become temporary or permanent residents, or even citizens. They do not support measures to apprehend and deport those here illegally.
What's the Problem?
The closest to a serious effort to address overpopulation is the approach being taken by Republicans trying to cut immigration to the US sharply. But they are doing so in a crude, inefficient manner, insulting immigrants, and not advocating use of E-Verify, a computerized data base that greatly facilitates the process of determining if a person is here legally . This is clearly the most effective tool to discourage illegal immigration.
We could do a lot to stop the torrent of people streaming across our borders by ending our support for the brutal governments of such countries as Guatemala, and by helping poor people in these countries via an expanded Peace Corps .
The Democrats, ignoring the negative consequences of opening our borders to all comers, attack Trump's approach, and disseminate pictures of little children in distress while trying to cross the Rio Grande. They oppose all efforts to stop the flow of people into the US, or to apprehend and deport those who succeed in penetrating to the interior of our country. A number of city governments have refused to allow police to participate in finding and apprehending illegal immigrants.
Democrats express no concern over the large number of Americans living in poverty, or near poverty, who are the immediate victims of immigration, legal and illegal. The super-rich, who run the country, are obviously happy to see the low wages resulting from the open borders that allow people from all over the world to come here and take jobs for very low pay .
Engineers and scientists are also being imported from low-pay countries, particularly India and China. They are willing to work hard, under unpleasant conditions, for minimal pay and little or no job security. Many from China and India come here as college students and, sometimes, even before graduation, take jobs in technology. Some remain here and become permanent residents or citizens. Others, after acquiring useful experience, return to Asia .
The prospect of having to compete for jobs with people from poor countries is discouraging many young Americans from studying science and engineering. More and more of them are opting for careers in finance, which are much more lucrative.
It is interesting that the billionaire Donald Trump is attempting to reduce our massive imports from China and other low-wage countries. Such imports are another major factor in the deindustrialization of our country.
It has been pointed out, correctly, by supporters of the status quo that most economists argue that immigration does not have negative effects on American wages. This argument, which directly contradicts the law of supply and demand, is clearly motivated by the fact that the great majority of economists are paid directly, or, if academics, indirectly, by organizations funded by the wealthy.Benefits of Real Borders
If our borders were closed to immigrants (except for a relatively small number of real victims of persecution in their home countries, or some people with unusual skills), then the only way to attract people into agricultural work would be to pay decent wages, and make the work less tedious, via appropriate use of technology. This would increase the cost of agricultural products, but by a good deal less than the increase in wages, because farm labor costs account for only about 20% of the retail prices of these products . The effect on prices of a 40% increase in farm worker earnings would, at most, increase annual spending on farm products by the average U.S. household by a barely noticeable amount.
Once our borders are secure, and illegal immigrants have left the country, apart from the benefits to those who would then be able to get better jobs, we would also be in better position to deal with the difficult problems associated with excess population.What has Happened to Education in the US?
Public education was once a major factor in making the US a real democracy. Regardless of the financial status of their parents, every American had a chance to get a decent education. The situation in this regard has been deteriorating for at least a half century. An important factor contributing to this situation is that pre-college education in the US is usually financed largely by local taxes. In poor areas, where income from such taxes is very low, teachers are underpaid and textbooks, libraries, shops, and other facilities are woefully inadequate. So schools are doing a poor job. Children in these areas, who seldom get effective help from their parents, are unlikely to qualify for the higher eduction that would facilitate their emergence from poverty.
As a graduate student at MIT, the tuition during my last year (1956-1957) was $1100. For 2019-2020 MIT tuition is $53,450 per academic year. The inflation factor from 1956 to 2019 was about 10, so, in real dollars, MIT tuition increased by a factor of about 5 from 1956 to 2019. These numbers would apply roughly to other top-ranked universities, and I believe that something similar occurred at lower ranked institutions. As a result of scholarships, a research assistantship, and good summer jobs, I had money in the bank when I completed my formal education. In recent years it is common for graduating students to be 30 or 40 thousand dollars in debt. The situation would be significantly worse if it were not for scholarships awarded to many students.
It is essential that the quality of American education, starting at the lowest levels and extending thru graduate school be improved, and that the cost to students and their families be greatly reduced. This has been done in many European countries. Tuition there is far lower than in the US.
 Homeland Security, "Verify Employment Eligibility (E-Verify)", March 26, 2019