Supporters hold signs at a rally in Bloomfield Hills, Mich., on Jan. 26. (AP) (Paul Sancya/AP)

One of the remarkable aspects of President Trump’s decision to allow funding to lapse for a large part of the government to secure money for a wall on the border with Mexico is how few people were persuaded by his crusade. Past polling has made clear how few minds were changed during the month-plus-long shutdown, but a poll from Gallup released Monday makes the point succinctly.

In June, 41 percent of Americans supported expanding the wall on the southern border while 57 percent opposed — a difference of 16 points. In the most recent poll, that gap expanded to 20 points, as strongly held views of the questions grew.

(Philip Bump/The Washington Post)

However else you feel about Trump’s advocacy for the wall or the shutdown, one point seems indisputable: His rhetoric isn’t moving people very much.

Another part of that poll, though, suggests that Trump is moving the political needle on immigration. Since 2016, the percentage of Americans who say immigration should be expanded has increased consistently, growing from 21 to 30 percent of Americans. That puts it at about the same percentage of Americans who say immigration should be decreased, a figure that fell over the past few years.

(Philip Bump/The Washington Post)

Aha!, one might think. Trump’s position on immigration seems to be having an inverse effect, persuading Americans to be more broadly supportive of expanded immigration. But when you step back, you see that this isn’t really the case.

Since about the mid-1990s, support for immigration has grown while opposition to it (as expressed by the number of Americans saying immigration should be decreased) has fallen.

(Philip Bump/The Washington Post)

The pattern has been uneven, but it’s unmistakable. If we isolate the trends since 1995, the chart for each response looks something like this.

(Philip Bump/The Washington Post)

The percentage of people saying immigration should stay at current levels has increased a bit, but the density of those advocating for an increase has, coincidentally, generally increased and those arguing for a decrease decreased.

What’s driving that? One likely factor is that the population has grown increasingly nonwhite over that same period. In 1980, about 80 percent of Americans were white non-Hispanic. By 2020, it’s estimated that fewer than 60 percent will be.

(Philip Bump/The Washington Post)

Overlapping with that is the increase in the density of foreign-born residents of the country. From a low in 1970, the density of immigrants has grown steadily over the past 50 years and is expected to hit 14 percent by next year.

(Philip Bump/The Washington Post)

It seems natural that a more diverse, more immigrant-heavily population would be more receptive to immigration. Other trends, like unemployment, which might seem like drivers of views on immigration, have been more consistently chaotic and don’t correlate to the shift in views of immigration. The ones above correlate well.

The implication, then, is that the increase in support for immigration is largely independent of Trump, not driven by him. But that doesn’t mean that there’s no connection between the two.

Let’s go back to the first graph. We’ve added a box, highlighting shifts in 2014.

(Philip Bump/The Washington Post)

From February to June 2014, the difference between the increase and decrease positions on this question grew from 9 to 19 points. The percentage of people saying they thought immigration should be decreased spiked to 41 percent, the highest it had been since 2011.

Why? In part because of media attention on a surge in children fleeing violence in Central America who came to the U.S. border, attention which in part leveraged concern about how the United States was changing. This immigration crisis spurred a strong backlash particularly in conservative media, and brought immigration to the forefront of American political concerns. (In July of that year, 17 percent of Americans identified it as the most important political issue, with twice as many Republicans as Democrats citing illegal immigration as a problem.)

Trump’s willingness to embrace the rhetoric deployed in the conservative media when he launched his campaign the following year quickly earned him a loyal base of support in the Republican Party, a base that helped power him to the top of the crowded field in the 2016 nominating contest. That blip in concern about immigration almost certainly helped elect Trump president.

For the most part, though, he doesn’t seem to have done much since his inauguration to push Americans in one direction or another on the subject.