Donald Trump points to a supporter at a rally in Mount Pleasant, S.C., in December, when he called for a ban on Muslims entering the United States. (Randall Hill/Reuters)

Khaled A. Beydoun is an associate professor at the University of Detroit Mercy School of Law and an affiliate faculty member at University of California at Berkeley.

Donald Trump’s calls for a ban on Muslims entering the United States and, more recently, for “extreme vetting” of anyone seeking to immigrate to the United States have been condemned as breaks from the nation’s traditions of religious tolerance and welcoming immigrants. Actually, Trump’s proposals reflect a long-standing, if ugly, strain of U.S. immigration policy, one that restricted the entry of Arab and South Asian Muslim immigrants and barred them from becoming citizens until the middle of the 20th century.

The Naturalization Act of 1790, which limited citizenship to “any alien, being a free white person,” drastically restricted the ability of Muslims to become citizens. The requirement meant that immigrants seeking lawful residence and citizenship were compelled to convince authorities that they fit within the statutory definition of whiteness. Arabs, along with Italians, Jews and others, were forced to litigate their identities in line with prevailing conceptions of whiteness — which fluctuated according to geographic origin, physical appearance and religion. Courts unwaveringly framed Islam as hostile to American ideals and society, casting Muslim immigrants as outside the bounds of whiteness and a threat to the identity and national security of the United States.

During a speech in Youngstown, Ohio, Republican presidential nominee Donald Trump outlined some of his plans to defeat the Islamic State and protect the United States. (Sarah Parnass/The Washington Post)

Long before 9/11 and the war on terrorism, U.S. courts painted Islam as more than merely a foreign religion, but rather as a rival ideology and “enemy race.” In a notable 1891 case, the Supreme Court highlighted “the intense hostility of the people of Moslem faith to all other sects, and particularly to Christians.”

Scores of Muslim immigrants were turned away at U.S. ports in the late 19th and early 20th centuries. Christian immigrants suspected of secretly being Muslims were also excluded. In 1913, a South Carolina court rejected the citizenship petition of a Lebanese Christian, saying that his skin complexion, “about [the color] of walnut, or somewhat darker than is the usual mulatto of one-half mixed blood between the white and the negro races,” provided evidence of miscegenation with Muslims. Ahmed Hassan — a native of Yemen and the first Arab Muslim to apply for citizenship — was denied naturalization in 1942, because, a court said: “It cannot be expected that as a class they [meaning Arabs, a term used synonymously with Muslims at the time] would readily intermarry with our population and be assimilated into our civilization.”

The United States’ functional ban on Muslim immigration persisted until 1944, two years before Trump’s birth. It was shifting U.S. geopolitical interests, not evolving perceptions of racial or religious inclusion, that drove dissolution of the restrictions. The post-World War II era saw the United States in direct competition with the Soviet Union over regions of influence, including the Arab world. The naturalization of Arab Muslim immigrants promoted the broader project of enhancing the United States’ profile in strategically important nations, most notably oil-rich Saudi Arabia. Indeed, the first court ruling to grant naturalization to an Arab-born Muslim was for a Saudi man, in Ex Parte Mohriez, in 1944 — and, even then, based only on the finding that Arabs should be considered part of “the white race.”

Despite the Mohriez decision, the Naturalization Act remained the law of the land until 1952, and restrictive immigration quotas stayed on the books. These quotas sought to “preserve the ideal of U.S. homogeneity” and prevent the entry of Muslim immigrants. Before 1965, the Muslim American population was overwhelmingly composed of native-born African Americans. The dismantling of the Naturalization Act and immigration quotas opened the door to immigrant Muslims from various corners of the Arab world, South Asia and Africa, boosting the U.S. Muslim population from 200,000 in 1951 to more than 1 million in 1971.

Today in the United States, Islam is practiced by 8 million people, a growth rate higher than any other faith group. But the threat of the Islamic State and intensifying Islamophobia has Trump, more openly than any other politician, actively revisiting America’s dark chapter of xenophobia and anti-Muslim animus.

In that sense, “Make America Great Again” is far more than a campaign slogan. It is a racial plea that evokes a time in the United States when whiteness was the legal hallmark of American citizenship, and Muslim identity the embodiment of everything un-American.