Listening to a certain brand of conservative immigration restrictionist, you'd think America was packed to the gills, unable to accommodate a single additional person.

This couldn't be more wrong. Indeed, America desperately needs more people.

In a recent Washington Post op-ed, former Trump White House national security spokesperson Michael Anton asked, "Why do we need more people? … For the extra traffic congestion? More crowded classrooms? Higher greenhouse gas emissions?" He argued that in fact America doesn't need more people, and further immigration here benefits only vote-seeking Democrats and cheap-labor-seeking Big Business. President Trump made a facile version of the same point when he reportedly told members of Congress earlier this week that his new immigration proposal is "I'm sorry, you can't come in."

The rest of the Republican Party isn't necessarily with Anton and Trump yet. But they're getting there.

Last summer, for instance, Trump endorsed a bill from GOP Sens. Tom Cotton of Arkansas and David Perdue of Georgia that would reduce legal immigration to roughly 500,000 annually over a decade, down from the current level of about 1 million. But even that's still a half million too many for the Trump-inspired "American Greatness" movement, of which Anton is a leading "thinker."

Before joining the Trump administration, Anton achieved recognition in Washington wonkdom as author — under the pseudonym Publius Decius Mus — of the 2016 viral essay "The Flight 93 Election." The title is an overwrought reference to the plane brought down by passengers on 9/11. To vote for Trump, according to Anton, was to "charge the cockpit" and seize control of the country from terrorists — meaning progressives, Hollywood, universities, establishment Republicans, Black Lives Matter, globalists of all sorts — anyone trying to crash and kill the American Project, as he defines it.

Anton is now affiliated with the American Greatness website, which tries to turn Trump's nationalist populist impulses into a serious political philosophy with coherent policy ideas. And to be sure, ending immigration is an idea, a big one given America's self-identification as a nation of immigrants.

But it's also a bad idea, as is clear from Anton's breezy reasoning in a piece employing the "spaghetti" theory of debate: Throw as many arguments as possible against the wall, specious or not, and hope a couple stick. That's long been the problem with the anti-immigration crowd, which can't quite decide on a plausible theory of their case as it hopscotches from one to the next.

It must be all very confusing for the average Republican. First, they were told the immigration problem was "illegal immigrants" undermining "law and order" just by coming here. Even worse, many were dangerous, as Donald Trump has infamously claimed. But one political problem with that argument is that immigrants make for a sympathetic group — even undocumented ones — given that they are coming here to better their lives. Then there's the reality that even as the immigrant population has risen over recent decades, crime has declined, even in areas with lots more immigrants.

Republican voters have also been told immigrants are bad for the economy, particularly the "low-skill" immigrants who supposedly hurt American wages. But again, the evidence suggests this argument is also weak. A 2016 literature review by The National Academies of Science, Engineering, and Medicine found immigration has an "overall positive impact on long-run economic growth in the United States." Some of America's most important companies were founded by first- or second-generation immigrants. And to the extent immigration hurts wages, the negative consequences are most likely to be found for "prior immigrants or native-born workers who have not completed high school." That sounds like an education and training issue, not an immigration issue.

But the silliest argument is that somehow America is filled to the brim and just can't comfortably fit any more people — you know, all that rush-hour traffic and those long lines at the airport. If so, then perhaps in addition to stopping immigration, Washington should also discourage parents from having too many children. Maybe a federal child tax instead of a child tax credit.

Of course America isn't all filled up. It is one of the least population dense countries in the world. Moreover, there are plenty of other advanced economies where the inflow of immigrants as a share of the population is higher than the United States, and whose stock of immigrants as a share of the population is higher as well. Doubling or even tripling the current million a year in legal admissions would be a smart policy for a country facing an economic growth and fiscal challenge from an aging population and slowing labor force growth. Worried about the decline in startup businesses? Slowing population growth in the West, Southwest, and Southeast regions since the early 1980s appears to be a major factor.

But none of that matters if the real reason you want to limit immigration is because you either think any population growth anywhere is bad for the environment — which maybe Anton does since he is oddly worried about carbon emissions — or you are just plain uncomfortable with the cultural, ethnic, and racial change that immigration can bring.

In that sense, the real question that the so-called "American Greatness" nationalist populists are asking isn't "Why does America need more people?" but instead "Why does America need more of those people?"