Volumes of research and centuries of experience do not bear out claims that immigrants “take our jobs,” don’t learn English, and fail to assimilate. But the idea that immigrants could vote to upend our relatively free economy has an air of credibility. It is arguably the best argument against liberalizing immigration.

Although immigrants are a boon to our economy and their children do reliably assimilate, immigrants could kill the goose that lays the golden eggs by undermining our free market institutions. In other words, will they come here, become citizens, and vote socialist, populist, or worse?

Fortunately, there is little evidence that immigrants make countries less free.

The United States has the 12th freest economy in the world, but most immigrants are from societies that are markedly less free than ours: the top three immigrant—sending countries in 2013 were China, India, and Mexico, ranked 115th, 110th, and 91st, respectively. If immigrants bring the impoverishing institutions of their homelands with them, the long—run economic impact of immigration could turn negative.

In a recent academic paper, my coauthors and I compared economic freedom scores with immigrant populations across 100 countries over 21 years. Some countries were majority immigrant while some had virtually none. We found that the larger a country’s immigrant population was in 1990, the more economic freedom increased in the same country by 2011. The immigrant’s country of origin, and whether they came from a poor nation or a rich one, didn’t affect the outcome.

These results held for the United States federal government but not for state governments. States with greater immigrant populations in 1990 had less economic freedom in 2011 than those with fewer immigrants, but the difference was small. The national increase in economic freedom more than outweighed the small decrease in economic freedom in states with more immigrants.

A related worry is that immigrants and their descendants would vote to expand welfare benefits for themselves. State governments can set the benefit and spending levels for welfare programs in their own states, and they also have varying levels of immigration and ethnic diversity. This provided a perfect opportunity for economist Zac Gochenour of Western Carolina University and me to test how immigrants affect welfare.

A state’s population of immigrants, illegal immigrants, Hispanics, Asians, ethnic or racial diversity caused by immigration, or any combination of the above did not affect the size of welfare benefits. Larger populations of immigrants or more diversity didn’t decrease welfare on the state level, but they didn’t increase it either.

Immigrants and their descendants could also potentially change policies through their opinions. If immigrants and their descendants had consistently different policy opinions and expressed those differences through voting, they could shift public policy.

To measure this, Sam Wilson from George Mason University and I looked at polling of immigrants and their descendants in the General Social Survey, a huge national survey of public opinions.

Other surveys by ethnicity are unreliable because many descendants of Hispanic immigrants do not self—identify as Hispanic. But the GSS allowed us to track the specific opinions of immigrants and their direct descendants so we could gain a more accurate assessment of their opinions by generation.

The results were stunning: Immigrants have opinions barely discernible from those of native—born Americans.

Nonetheless, there are two issues where first—generation immigrants do reliably display different opinions: They are more likely to self—identify as political independents, and they broadly favor government involvement in the economy.

The political independence of immigrants in a new country is not surprising, but immigrants’ support for government is. However, focusing on specific policies, immigrants’ generic support for more government does not translate into support for higher taxes, or more entitlement spending, or more welfare. That bodes well for preserving America’s free—enterprise system.

Furthermore, the children of immigrants have opinions that are identical to those of Americans who have been here for at least four generations. There simply is not a growing bloc of immigrants and their descendants who will vote to overturn free markets.

There are at least five hypotheses that could explain why immigrants don’t affect economic policy in the United States.

The first is called the doctrine of first effective settlement: It is very hard to upend established political and economic institutions through immigration. Immigrants change to fit into the existing order rather than vice versa.

The second possibility is immigrant self—selection: Those who decide to come here mostly admire American institutions or have opinions on policy that are very similar to those of native—born Americans. As a result, adding more immigrants who already broadly share the opinions of most Americans would not affect policy.

The third idea is that naturalized immigrants have opinions that are identical to American citizens, while non—naturalized immigrants do not. Either those who decide to naturalize don’t want to change American institutions, or the process of naturalization itself changes the opinions of immigrants.

The fourth explanation is that immigrants and Americans actually have very similar policy opinions. This hypothesis is related to those above, but it indicates an area where Americans may be unexceptional compared to the rest of the world. According to this theory, Americans are not more supportive of free markets than most other peoples, we’re just lucky that we inherited excellent institutions from our ancestors. (This argument does not make sense by itself, but certain elements of it could be true.)

The fifth reason is that liberal immigration laws make native voters oppose welfare because they believe immigrants will consume those benefits (regardless of the fact that poor immigrants actually under—consume welfare compared to poor Americans). In essence, voters hold back the expansion of those programs based on the belief that immigrants may take advantage of them.

As Paul Krugman aptly observed, “Absent those [immigration] restrictions, there would have been many claims, justified or not, about people flocking to America to take advantage of [New Deal] welfare programs.”

In other words, Roosevelt’s New Deal and Johnson’s Great Society programs could only have been created because they were passed during one of the lowest points for immigration in US history — thus removing the most effective political argument against expanding welfare.

As the late labor historian (and immigration restrictionist) Vernon M. Briggs Jr. wrote, “This era [of immigration restrictions] witnessed the enactment of the most progressive worker and family legislation the nation has ever adopted.”

None of those programs would have been politically possible to create amidst mass immigration. Government grows the fastest when immigration is the most restricted, and it slows dramatically when the borders are more open.

The most plausible argument against liberalizing immigration is that immigrants will worsen our economic and political institutions, thus slowing economic growth and killing the goose that lays the golden eggs. Fortunately, the academic and policy literature does not support this argument: even the best argument against immigration is still unconvincing.