On July 9, 1868, the 14th Amendment to the U.S. Constitution became law and granted birthright citizenship to all those born in the United States who are under the jurisdiction of the U.S. government. The purpose of the citizenship clause of that amendment was to overturn the 1857 Dred Scott v. Sandford decision, in which the Supreme Court ruled black Americans could never become citizens.

Although it was intended to rectify inequities left over from slavery, the 14th Amendment unintentionally created a peculiarly American-style of citizenship that we should all appreciate on the 149th anniversary of its ratification.

The 14th amendment states: “All persons born or naturalized in the United States and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.” In the 1898 case of United States v. Wong Kim Ark, the Supreme Court ruled that the children of all immigrants, including those who could not naturalize, are citizens. Since then, the 14th Amendment has applied to all children of all immigrants — both legal and illegal.

The result of universal birthright citizenship is security. Those born here can rest assured that they will not be stripped of citizenship. Minorities of any kind are protected (with some exceptions like the internment of some Japanese-Americans during World War II) by birthright citizenship. As a result, the descendants of immigrants are legally equal to any other American and can assimilate, accumulate property, and put down permanent roots in the land their parents chose.

At least on paper, this concept of American citizenship includes all those born here and those who naturalize. It is in stark contrast to the ethnic-based citizenship that dominated the world then and now. This was likely due to necessity, as the notion of an “ethnic American” is a plainly absurd, given the diverse and fractionalized ancestry of modern Americans. The 14th Amendment helped expand membership in the American polity to everybody born here, regardless of the capricious whims of legislators, thus making those diverse people into loyal citizens.

The cultural and social acceptance of Americans regardless of their race, ethnicity, religion, and other characteristics took longer than the legal acceptance. Americans frequently viewed others born here who were black, Asian, or Catholic as less American, but after the 14th Amendment they all had citizenship. By granting citizenship to all those born here, despite the prejudices of their times, the descendants of those immigrants became American without facing much legal discrimination. The legal and cultural discrimination and prejudice that did persist was easier to overcome for citizens than for a stateless mass of American-born non-citizens. Thus, the American social and cultural conception of citizen eventually expanded to include blacks and the descendants of all immigrants.

Former President Ronald Reagan recognized this. In a 1988 speech he stated that “An immigrant can live in France but not become a Frenchman; he can live in Germany but not become a German; he can live in Japan but not become Japanese, but anyone from any part of the world can come to America and become an American.” American-style citizenship encouraged the children of immigrants to assimilate, preventing the growth of a class of U.S.-born people who are not citizens.

Recent research has confirmed Reagan’s observations. For example, University of Washington economist Jacob Vigdor found that the pace of modern immigrant civic and cultural assimilation is similar to that of immigrants from the early 20th century, who themselves quickly assimilated. Vigdor’s conclusion is reassuring if you consider the assimilation of Eastern European, Jewish, and Italian immigrants to be a success: “Basic indicators of assimilation,” he wrote, “from naturalization to English ability, are if anything stronger now than they were a century ago.”

However, immigrant integration and assimilation is not going as well in Europe.

The lack of birthright citizenship in Europe makes assimilation more difficult, especially for the descendants of Muslim immigrants, who have some persistently divergent opinions and outcomes — especially lower participation in the workforce. Youths born to noncitizen immigrants in countries without birthright citizenship are in a legal underclass, but have no place to go and no reason to be loyal to the countries in which they are born.

The German-born children of Turkish, Tunisian, and other guest-workers from the mid-20th century were mostly not allowed to become citizens until 1999. The same was true in Japan, where Koreans born on Japanese soil, called zainichi, were barred from citizenship for generations and still self-identified as foreign after four generations. In both countries, these noncitizen youths are more prone to crime and extreme political ideologies like Islamism in Germany or communism in Japan.

In the U.S., by contrast, children of immigrants are legally on the same playing field as children born to American citizens. Both can serve in the military, purchase firearms, serve on juries, and be treated the same by the legal system. That is one reason why 89 percent of second-generation Hispanics and 96 percent of third-generation Hispanics have described themselves as American only , according to the Pew Research Center. “Hispanic-American” or “Mexican-American” is still popular among some after several generations, just as “Italian-American” still survives, but these Americans do not view themselves as foreigners.

Occasionally politicians argue for repealing birthright citizenship to exclude the children of illegal immigrants born on U.S.-soil — as Donald Trump did as a candidate for President. Yet granting citizenship to those born here is an insurance policy for a poorly functioning immigration system, because it encourages the roughly 4.7 million U.S.-born children of illegal immigrants and roughly 275,000 born to them in 2014 to assimilate.

And it’s not just modern Europe where we see what happens in the absence of birthright citizenship. Republican Rome tightened citizenship after the Second Punic War by disallowing noble families to naturalize and halting grants of citizenship to loyal allies. The new restrictions led to an uprising in cities pushing for Roman citizenship — one of the stranger civil wars in history. To quiet the unrest, Rome finally reinstated the older rules that had served it so well. America doesn’t face a revolt of allies demanding citizenship, but the current challenge of assimilating the children of immigrants born here is much easier to overcome when they are all citizens.

The 14th Amendment was a partial corrective to slavery and racist court decisions, but that should not blind us to how it has also helped to expand the sphere of American citizenship while strengthening America. The descendants of immigrants are assimilating well in part due to birthright citizenship. Republicans should be proud that they are members of the political party that supported the amendment and made all of that possible.