There are ~30,000 PGY-1 spots and only about 18,000 allopathic medical school graduates. (1) All the native allopaths and all the osteopaths together can't fill all the residency spots. We inhale foreign medical graduates.
There's 31,757 positions offered. However, if you are applying into a specialty, you apply simultaneously for a PGY1 and PGY2 position, so those people are being double counted.
As a result, you need to subtract 2,677 advanced positions from the 31k positions, yielding 29,080 PGY1 + PGY2. There are 18,539 US MD applicants, but with the merger of the ACGME and COCA, DO applicants must be counted, adding 3,590 to the US graduate pile. That gives 22,129 US graduates competing for 29,080 spots. Yeah we take a lot of "foreigners" but a lot of them are actually American citizens who went to school in other countries and many of whom have US medical education debt, 5,069 in fact (look on page 1, "IMGs"). If you add in the IMGs, that's 27198 US graduates and US citizens applying for 29,080 spots. Only space for about 2000 Foreign Medical Grads.
I just wanted to reply to this comment with the NRMP match data for 2016. It's a pdf that we all use when applying for residency. Perhaps some people might find the information regarding each specialty's available positions/applicant number/median scores/etc helpful.
When it comes to the admission process aren't all IMG's considered the same irrespective of citizenship. So 5069 (citizens) + (x non-citizens) compete for the remaining seats (6951). Isn't that correct?
IMGs (Citizens) and FMGs (foreign nationals who went) are considered slightly differently.
IMGs have the advantage of speaking English and have no potential visa issues.
This distinction will matter more and more as the race for residency spots tightens and the US becomes more insular, because a lot of IMGs have US educational debt. It also matters where the person went to medical school, e.g. US citizen who went to Israeli medical school vs someone who went to the Caribbean vs an Indian national vs an Iranian national who now will have visa issues with trump. Visa issues are huge, because no one wants to match someone who can't show up for work 2 months later.
These subtle distinctions are not easily sussed out by NRMP data, but the trend is that in the current era, IMGs have a slight advantage.
So what good does increasing US medical school graduation rates do? OK, it would displace some IMGs/FMGs from residency positions, but it doesn't ultimately create more doctors. You can't be licensed to practice independently in the US unless you enter a residency, take the USMLE Step 3 after intern year, and typically you also take a specialty board exam at the end of residency.
(1) Pages v and 14: http://www.nrmp.org/wp-content/uploads/2017/04/Main-Match-Re...