When President Trump’s supporters gathered on Pennsylvania Avenue last week to falsely claim that the presidential election had been stolen, I was reminded of how far the country has fallen since this eighth-grade Boy Scout marched 67 years ago on that same thoroughfare to celebrate a U.S. president’s inauguration.

Last Saturday’s crowd, interspersed with white nationalists and far-right activists, trudged eastward toward the U.S. Capitol, many carrying flags bearing Trump’s name.

That image sharply contrasted with the sight of some 600 Boy Scouts bearing American flags who marched westward toward the White House in honor of Dwight D. Eisenhower’s first presidential inauguration.

The Trump supporters’ march was a parade of anger and self-pity because the 45th president, to whom the marchers have given their allegiance, has lost. Defiance was on display. There were people, The Post reported, atop a U-Haul truck with a flag of a gun and the words “Come and take it.”

Conversely, the 1953 gathering was a festive welcome to the nation’s 34th president, in a scene I have written about before. More than 750,000 spectators, 25,000 marchers, 75 bands, 59 floats, cowboys, members of the armed forces, a 280mm cannon that was longer than the White House reviewing stand, horses and elephants, and blimps overhead.

How far we have fallen from the White House of my youth, the symbol of our nation, to the now-besieged Executive Mansion hidden away within a fortified zone surrounded by nearly two miles of fencing.

Yes, we marched the same stretch of L’Enfant’s “grand avenue” as the Trumpites did. But our path led to the presidential reviewing stand, where the nation’s chief executive stood ramrod straight and greeted us with his black homburg over his heart. There were cheers and laughter at our end of the avenue.

Last week, violence broke out between some of Trump’s people and counterprotesters only five blocks from the White House. Some went home bloodied. In ’53, the crowd went home happy.

The Lafayette Square that I passed at least twice a day traveling to and from high school is now barricaded by unscalable fencing. This is the same Lafayette Square that once served as a bus transfer station and a place to exercise First Amendment rights.

And to think: My Washington Times-Herald daily newspaper route required me to walk past the president’s guesthouse, Blair House, to deliver the morning paper to a building on Jackson Place adjacent to Lafayette Square. Today, the entire area is off-limits.

The White House contrast between then and now is clear, too.

Washington, D.C., was voteless in 1953 in presidential elections. The 23rd Amendment, which gave the city three electoral votes, was still eight years away.

But our folks, on the outside looking in, had favorites.

King family adults liked President Harry Truman because of his outspoken stance on civil rights and desegregation of the armed services. Truman’s support for Illinois Gov. Adlai Stevenson may have also tilted the family toward Stevenson, who lost in a landslide to Eisenhower in November 1952.

That didn’t stop me from representing the Scout troop sponsored by 19th Street Baptist Church (which now sits on 16th Street) and participating in Eisenhower’s inauguration.

Eisenhower was an acclaimed hero who had turned the tide of World War II — a war that took its toll on American forces without regard to race, color or creed. He commanded NATO forces in Europe. Now, there was a war going on in Korea. Thousands of Americans had died. Eisenhower said during the campaign that he would “bring the Korean War to an early and honorable end.” And his pledge that if elected, “I shall go to Korea,” resonated with a war-weary public.

It was okay to march in this Republican’s parade.

Consider how far have we fallen.

From a president of Eisenhower’s stature to today’s crude and malignant Trump, who, since taking office in 2017, has worked to turn back the clock on civil and human rights, abused the Constitution and is now, with no sense of shame, undermining the democratic process to save his own skin.

How far fallen?

From a president who was a five-star general and former supreme commander of allied forces in Europe to a president who avoided military service and expressed confusion over why anyone would choose to serve. Trump disputes the charge that he called U.S. servicemembers injured or killed in war “losers.” Do you take his word for it?

How far have we fallen? Look no farther than the White House.