Republican presidential nominee Donald Trump speaks at a campaign rally in Bedford, N.H., on Thursday. (John Locher/Associated Press)

How about we hold off on dancing in the end zone in celebration of the new National Museum of African American History and Culture? And let’s quit wasting time in pursuit of black celebrityhood. What about the danger staring us in the face?

The prospect of a Donald Trump White House presents African Americans with the most consequential presidential election since the 1876 race between Republican Rutherford B. Hayes and Democrat Samuel J. Tilden. That 19th-century contest ultimately derailed efforts to extend the full rights and privileges of citizenship to freed African Americans. Unless folks of color get off our duffs, history may well repeat itself.

To recall, the 1876 election wound up in an electoral-college dispute over ballot returns from three Southern states under Reconstruction control. To break the stalemate, Republican surrogates of Hayes met with a delegation of Southern Democrats to hammer out a deal: The Southerners would not stand in the way of a Hayes victory if Hayes agreed to withdraw all federal troops from the South, thus leaving former slaves unprotected.

The sellout, dubbed the Compromise of 1877, ironically occurred here in the District, at the Wormley House at 15th and H streets NW, a hotel owned by black entrepreneur James Wormley.

The deathblow to Abraham Lincoln’s post-slavery democratic experiment was delivered by Hayes. But he didn’t single-handedly kill Reconstruction. A combination of judicial and executive actions, plus entrenched racism, did the job.

There is a lesson about those times that could be applied to circumstances of today.

Hope was alive back then.

Lincoln signed the 13th Amendment outlawing slavery. The 14th Amendment was adopted granting citizenship to blacks and guaranteeing due process and equal protection. The 15th Amendment guaranteeing black men the right to vote was ratified. Congress passed the Civil Rights Act of 1875 guaranteeing African Americans equal rights in public facilities and jury duty.

All that brought joy, much like the 1954 school desegregation decision, and the civil rights and voting rights acts of the 1960s.

As with today’s black celebrants, Reconstruction-era African Americans had reasons to feel upbeat about the future.

But then, as is happening now, the Supreme Court helped undo the good that was done.

The high court declared the act of 1875 unconstitutional, ruling that Congress lacked the power under the 14th Amendment to grant equal protection under the law to blacks — that only states and local governments could do that. Through other rulings, the court kneecapped civil rights protections for decades to come.

Andrew Johnson, who became president after Lincoln’s assassination, also undercut Reconstruction’s positive measures. He gave former Confederate states freedom to manage their affairs, which allowed them to enact black codes that imposed plantation-like conditions on former slaves.

But it was sweeping white backlash against changes to the country’s racial caste system that plunged the dagger into the heart of Lincoln’s political revolution. Reconstruction was replaced by white-created discriminatory political and social systems, vigorously enforced by law and custom for nearly 100 years. It took decades of protests, legal and legislative actions, and many broken black and white heads and bodies for the nation to begin to recognize and address slavery’s legacies.

Why this remembrance of things past? Because a Trump White House promises a repeat of America’s dark side.

Let’s sort out the danger in a Trump presidency.

He is, without question, an ignorant, undisciplined, ranting bully who exaggerates and lies without shame. He wears a tough-guy masculinity but is actually a coward who picks on women, demeans minorities and is thoroughly lacking in human decency.

Repulsive though he is, nominee Trump’s character defects aren’t what make him a threat. What does sicken and alarm, and what ought to concentrate African American minds, is the thought of Trump with the powers of the presidency in his hands. Therein lies the danger.

Think no further than the voting booth.

Assaults by Republican-controlled state legislatures on ballot-casting African Americans and other minorities are well underway. The path of those voter-suppression measures was greased by a 2013 Supreme Court ruling eviscerating the Voting Rights Act by hamstringing the Justice Department’s enforcement efforts. Echoes of the Reconstruction-era Supreme Court.

Now imagine a Justice Department under Trump’s control. It will be 1876 all over again. Hard-won changes will be reversed. “Make America Great Again” — the call for restoration of white supremacy — will come to pass.

Police and the black community? The chances of a Trump administration vigorously overseeing state and local law enforcement, imposing reforms on departments that show patterns of civil rights violations, and issuing federal mandates for change are unlikely. For goodness’ sake, the man likes “stop and frisk.”

Another scary thought? Form a mental image of a Trump Supreme Court justice.

Trump has already provided a glimpse of that nightmare. Examine his frightening list of right-wing court nominees. Install a Trump White House and say farewell to civil liberties, voting rights, consumer rights and reproductive rights, and hail gun supremacy.

One asinine argument heard among some black activists is that Hillary Clinton is not doing enough to motivate the African American community.

If the prospect of a Trump victory isn’t enough to drive blacks to the polls, nothing said or done by Clinton or anyone else, including President Obama, will do the trick.

Oh, well: Ignore the lessons of Reconstruction. Keep on dancing in the end zone.

Until they stop the music.

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