I think Canada and Mexico belong to two separate categories. It is true that the US benefits from highly educated immigrants from Canada AND Mexico. In fact, th

I think Canada and Mexico belong to two separate categories. It is true that the US benefits from highly educated immigrants from Canada AND Mexico. In fact, the US benefits in this regard much more from India and China, than Canada and Mexico, which simply do not have the depth of the talent pool required to sustain US supremacy. But the massive influx of immigrants from Mexico (and Central America) over the decades has not been of this kind. It has mostly been low-skilled or unskilled workers who form a growing underclass that can not participate effectively in civic society. Of course, from the standpoint of sustaining population growth to slightly above replacement levels, immigration of unskilled/low-skilled immigrants is still a good thing. Unfortunately, the US population growth flattened out or went slightly into reverse in 2020. Whether this trend takes hold is anybody's guess, but given America's declining appetite for immigration in general, the worse may still be ahead of us. As you say, though, automation may make slower population growth moot. Who knows!