The Trump immigration plan is a bit more of a compromise than many expected.

That includes members of his own party, whose objection to a path to citizenship for Deferred Action for Childhood Arrivals recipients will be a barrier to passing the proposed legislation. The conciliation on DACA is supposed to be paired with $25 billion to extend the border wall, in order to garner enough support on both sides to get legislation through. There are things both sides hate, but support for DACA recipients polls well and support for the border wall is opaque and kind of a toss-up.

What sometimes doesn't get as much attention as the well-trod DACA and wall debates is that the plan would dramatically cut legal immigration. As Ed Kilgore—a veteran Democrat insider—writes at New York, that actually polls OK, depending on how you look at the the numbers and how the questions are phrased. Either way, it doesn't poll badly.

And maybe it shouldn't. Masha Gessen writes in the New Yorker that "a different approach to thinking about immigration would frame the issue in purely moral terms rather than largely economic ones," and that arguing on behalf of sustained or greater legal immigration as an economic benefit cedes too much ground to the meritocratic system the Trump administration is pushing.

Gessen's argument is worth taking seriously, but there's a reason Democrats put forth the economic-benefit perspective: Cutting legal immigration seems to poll well, or at least well enough to be politically viable—even though putting America First doesn't seem like it actually will bring economic benefits.

Take this finding by University of Chicago economist Ufuk Akcigit in a recent NBER working paper (cited last year in BizEd): "We show that in the top 10 most inventive states in  terms  of  the  average  number  of  patents  per  capita  between  1880  and  1940,  20.6% of the population were international migrants, compared to just 1.7% of the population of the least inventive states." That's correlation, not causation, of course.

But this isn't: "The foreign-born," the authors write, "were more prevalent among inventors active in the U.S. than in the non-inventor population." Are immigrants just particularly inventive? Not necessarily; they argue that invention has a lower barrier to entry than credentialed fields like medicine or law, and therefore foreign-born people were more likely than American-born people to focus their energies on inventing.

Plus, there are long-run benefits from innovations that don't rise to the level of patents. In another NBER working paper, this one co-authored by Northwestern's Nancy Qian, the authors use railway expansion from 1850 to 1920 to make the case that immigration boosted manufacturing and agricultural output as well as "innovative activity," despite immigrants having considerably higher rates of illiteracy and lower rates of education. (Immigrant-heavy areas would become more educated in the long run, perhaps because the descendants of those immigrants pursued education more than their longer-established neighbors.)

Just as interesting as what they did is how they got there.

The best land was often granted to the railway companies by the Federal government in an attempt to promote the development of uninhabited territories. The railway companies, including the Union Pacific, Santa Fe, Burlington, Northern Pacific, among others, through a variety of mechanisms, intentionally promoted the settlement of these tracks of land contiguous to their railway lines, in part, to stimulate demand for the railway. They did this by selling the land cheaply and by encouraging immigrants from Europe to settle there. Common methods used to accomplish this were the establishment of advertising offices in Europe and subsidizing migrants’ trans-Atlantic travel.

The railways were a middleman in a process of seeding (literally) fallow land with people. Since the political impetus for the immigration debate ties back to the idea that those places are withering, it's worth considering how they got settled in the first place.