One of the first things America will do next year is mark the centenary of the death of our 26th president, Theodore Roosevelt. In his final days he had been preoccupied with the meaning of Americanism. He grappled with immigration. It was, it turns out, the topic of TR’s last public statement, which couldn’t be more relevant to the debate in the era of Trump.

“We should insist,” the ex-president said in a statement read at a meeting of the American Defense Society on January 5, the day before he died, “that if the immigrant who comes here does in good faith become an American and assimilates himself to us he shall be treated on an exact equality with everyone else.”

It would be, TR went on to say, “an outrage to discriminate against any such man because of creed or birthplace or origin.” But, he added, “this is predicated upon the man’s becoming in very fact an American and nothing but an American . . . we have room for but one soul loyalty, and that is loyalty to the American people.”

What is so striking about TR’s views on immigration is that, though he was a titan of the Progressive Era, his views on immigration align in many ways with President Trump’s. TR was an advocate of “a Scandinavian, a German, or an Irishman who has really become an American.” But he was hostile to admitting Asians and grappled with the political impact of others.

These included the wave of Eastern Europeans and Southern Europeans arriving at the turn of the century. TR could be personally sympathetic to these latter groups. So much so that Jewish Republicans printed flyers in Yiddish to support his 1899 New York gubernatorial campaign, and he was the first President to appoint a Jew to his cabinet (Oscar Strauss of Commerce). Two menorahs were displayed in his Oyster Bay home.

Yet Roosevelt wanted to screen out arrivals who might prove difficult to assimilate or impact wages. In 1906 he wrote to the American Federation of Labor: “We must not let our national sentiment for succoring the oppressed and unfortunate of other lands lead us into that warped moral and mental attitude of trying to succor them at the expense of pulling down our own people.”

“Laws,” Roosevelt added, “should be enacted to keep out all immigrants who do not show that they have the right stuff in them to enter into our life on terms of decent equality with our own citizens.”

Roosevelt signed the Immigration Act of 1907, the first federal statute to restrict new arrivals based on health or moral character. The measure created the Dillingham Commission, the first government entity appointed to study immigration in depth. The Commission’s final report marked the positive impact of immigration on the country.

It also recommended — as part of a 41 volume report issued in 1911 — a literacy test. It initiated the idea of entry quotas based on national origin. The literacy test was included in the Immigration Act of 1917, while the quota model was exploited in the postwar hysteria over immigration that led to the restrictive quotas for Eastern and Southern Europeans in the legislation of 1921 and 1924.

That legislation was co-sponsored by Roosevelt’s ally and fellow opponent of Woodrow Wilson, Senator Henry Cabot Lodge. In today’s terms, Roosevelt was no fan of multicultural diversity, insisting immigrants learn English and viewing those who clung to their native languages as “dwellers in a polyglot boarding house.”

Yet TR eschewed the xenophobia of the Republican restrictionists like Lodge, who wanted to preserve America for the Anglo Saxon and Germanic races. Roosevelt’s screening criterion for new arrivals from Europe was a family’s potential for assimilation, culturally and economically — a view not dissimilar from the Trump administration’s advocacy of a merit- based system.

Would Roosevelt have opposed the Johnson Act of 1924? That introduced the era of legal restrictions on immigration. My bet is that TR would have followed the route of President Coolidge, signing the bill despite serious misgivings. The national consensus in favor of restrictions was overwhelming (the cause made temporary allies of the American Federation of Labor and the Klu Klux Klan).

As the 116th Congress convenes a week hence, any solution to America’s immigration challenge will require compromise — a point marked by The New York Sun in 1919, when, the day after TR’s death, it issued an editorial that reflected the ambivalence with which it once endorsed him, which has been described as “Theodore, with all thy faults.”

The Sun called TR “an idealist in his ends, and an opportunist in his methods.” From his life the Sun drew the observation that “how to live for a future ideal, but in the actual present, how to face the facts as they are and not lose the ambition to make them better, is a perpetually shifting problem which no man can perfectly solve.”

Mr. Atkinson, a contributing editor of The New York Sun, writes on topics in 20th-century history. Image: “The Americanese Wall,” political cartoon of 1916. Library of Congress.