In 1958, John F. Kennedy, then a U.S. senator, published a small book aptly titled A Nation of Immigrants. The world was much different then, as new states in Asia and Africa emerged, while European colonialism retreated.

The West was in the midst of a post-war economic recovery, and there was demand for low-wage workers in a growing economy.

Kennedy’s book made the case for ending quotas on immigration based on national origins. His argument was also in keeping with the Cold War politics, of denying Soviet Union influence among the newly emerging countries at the expense of the U.S. depicted as a racist society.

Two years after President Kennedy’s assassination, his successor, Lyndon B. Johnson, signed into law the Immigration and Nationality Act of 1965. The U.S., as Kennedy had called for, adopted an open immigration policy and Canada followed soon after.

Kennedy celebrated in his book how much America, in its making, owed to immigrants. He wrote, “Since 1607, when the first English settlers reached the New World, over 42 million people have migrated to the United States.

“Another way of indicating the importance of immigration to America,” Kennedy observed, “is to point out that every American who ever lived, with the exception of one group, was either an immigrant himself or a descendant of immigrants.” The exception was the aboriginal people inhabiting the continent.

The act of leaving the old world for the new, Kennedy wrote, involved breaking with the past and embracing the future as immigrants braved the immense hazards in making the journey across seas and oceans filled with uncertainties. But inside a decade of Kennedy’s writing, the arrival of wide-body transcontinental jetliners brought about a revolutionary change in the means of travel, and with it the entire meaning of immigrants and the experience of migration were altered.

Then came Pierre Elliott Trudeau’s multiculturalism and this policy, together with the revolutions in global transportation and communications, meant immigrants arriving since the 1970s were more or less trading places without making any break with their old world cultures and loyalties.

As a result, what Kennedy wrote about earlier generations of immigrants may not be said to the same extent for new immigrants. In the new conditions of globalization, the distinction between migrant workers and immigrants became increasingly obscure.

Many among new immigrants — given the policy of multiculturalism and the acceptance of dual or multiple citizenships — are migrant workers landed as immigrants, who draw upon the benefits of the host country while remaining attached to the customs and values of their native country.

It is politically incorrect to probe the practical reality of what has come to pass in the half-century since Kennedy pushed for open immigration, but the growing disconnect evident among newly arriving immigrants with the culture of their host country is undeniable.

These are issues that need to be discussed openly and widely. Immigration is not merely about numbers, as I indicated in my previous columns. Its effects over time inevitably change, and not necessarily for the better, the host country’s culture.

Kennedy, in looking back, celebrated the overall positive outcome of immigration. In looking ahead, we are far more aware since 9/11 of immigration’s divisively negative side.