On Sept. 23, 1957, thousands of segregationists blocked nine young black students from enrolling in Little Rock Central High School, an all-white institution in the Arkansas capital. Gov. Orval Faubus ignited a nationwide crisis when he defied the Supreme Court’s landmark 1954 decision on desegregation, Brown v. Board of Education, and deployed the Arkansas National Guard to bar the students. Two days later, President Dwight D. Eisenhower ordered U.S. Army units to escort the Little Rock Nine into the school.

This fall marked the 60th anniversary of this pivotal moment in the history of America’s racial struggle. With the political landscape seemingly as divided as it has ever been, this moment provides an opportunity to examine the depth and contours of segregation in the nation today. Though clear advances have been made since the civil rights movement, the enactment of increasingly conservative social policies over the last half century reveals how tenuous such progress turned out to be.

The consequences of creeping racial resegregation should constitute nothing less than a national crisis.

U.S. cities have grown more segregated over the past 40 years, and persistent and intensifying racial disparities between white communities and people of color have emerged. This systematic resegregation has grave implications for access to health care services, education and accumulation of wealth.

In 1966, Martin Luther King Jr. described a health care system that was tantamount to medical apartheid. “Of all the inequalities that exist,” King said, “the injustice in health care is the most shocking and inhuman.”

The resegregation of U.S. cities has revived some of the same challenges in a variety of social arenas. Many African-American and low-income patients, for example, are largely shut out of major teaching hospitals, where the most advanced medical practices are available, according to a report issued this year by the Harvard Medical School and the Boston University School of Medicine. Consider that black people accounted for only 18 percent of patients in New York City teaching hospitals in 2014, but made up nearly one-third of patients in other city hospitals.