Correction: An earlier version of this column stated that Sandra Day O’Connor had replaced Lewis Powell on the Supreme Court. Ms. O’Connor replaced Potter Stewart. This version reflects the correction.

When the Gallup Poll asked Americans to identify the top challenge facing the country in July 1964, 60 percent named racial issues. In the summer of 2012, 1 percent picked race.

Obviously, these findings reflect the great distance the United States has traveled. Racial tension has never disappeared, and probably never will; take the Trayvon Martin incident. Yet even before Barack Obama’s election as president in 2008, racial peace was the dominant trend. Not even the 1992 beating of Rodney King by Los Angeles policemen, and the violence that followed the officers’ acquittal, fundamentally disrupted it.

In the American Interest, Walter Russell Mead credits a post-civil rights “Compromise of 1977,” encompassing such policies as race-conscious university admissions and the Voting Rights Act, which helped build a black middle class and boost minority representation in government from the White House on down.

Yet by the summer of 2013, that compromise could be shaken and race could once again roil American politics. That’s because the Supreme Court is poised to take up race-conscious admissions this week and, later this term, a key provision of the Voting Rights Act. And five conservative-leaning justices are on record as skeptics of both.

So it’s worth recalling that these policies have lasted as long as they have because of compromises — in which Republicans played a crucial part.

In 1977, white applicant Allan Bakke asked the Supreme Court to strike down a University of California program that awarded a fixed number of spots in medical school to African Americans and other historically disadvantaged minorities.

Justice Lewis F. Powell, an appointee of President Richard Nixon, crafted an opinion that forbid quotas, while permitting schools to take individuals’ race into account for “diversity.”

Powell’s amorphous rule satisfied neither civil rights advocates who saw quotas as compensation for past discrimination, nor critics to whom any use of race is “reverse discrimination.”

But it proved workable — increasingly so as prosperity lessened students’ sense that college admission is a zero-sum contest. Asked to overturn Powell’s ruling in 2003, the Supreme Court sustained it; Justice Sandra Day O’Connor, whom President Ronald Reagan appointed to replace Potter Stewart, wrote the key opinion.

In 1982, Congress considered an extension of the 1965 Voting Rights Act. The debate pitted a rising conservative movement against liberal civil rights organizations determined to expand the law’s scope. To oversimplify somewhat, the question was whether to regulate state practices that resulted not only in fewer minorities voting but also in fewer minorities being elected.

Congress approved a Powell-like standard barring proportional representation but taking account of “the extent to which members of the minority group have been elected to public office in the jurisdiction.” The architect of the compromise was then-Sen. Robert Dole, Republican of Kansas. Reagan signed it into law.

Subsequent history has shown the benefits and defects of each compromise.

Between 1976 and 2010, the African American share of college enrollment rose from 9.4 percent to 14.5 percent, according to the National Center for Education Statistics. The number of black elected officials rose ninefold nationwide between 1970 and 2000; Deep South states have made the most progress. This is revolutionary.

Still, using race as “one factor” has often become a euphemism for using it as the decisive factor. That understandably rubs many Americans the wrong way, especially in a multiethnic society that resembles the old white-black caste system less and less. And access is not the same as success: African American college students graduate at about half the rate of whites.

Race-conscious gerrymandering arguably fuels political polarization, in that it encourages the two parties to split the electorate into white and minority districts, then pitch them mutually exclusive policies. It’s not clear that minorities have more power as the dominant group in a non-competitive district or as the swing vote in a competitive one.

It’s in the nature of constitutional litigation for each side in these cases to play down such nuances. Each wants the court to rule clearly and unequivocally in its favor — to resolve the vexed questions once and for all.

I would agree — if I were equally confident that the rights and wrongs could be so readily defined, constitutionally or otherwise. But I’m not. A century and a half after Gettysburg, half a century after Selma and 35 years after Bakke, we still need practicality and compromise. We need the realism, and wisdom, of Powell, O’Connor and Dole.