Baltimore’s Adam Jones, left, and first base coach Wayne Kirby stand for the playing of the anthems as they wear No. 42 in honor of Jackie Robinson on the 70th anniversary of his first game in the major leagues on April 15. (Tom Szczerbowski/Getty Images)

In 1947, Jackie Robinson broke the color barrier in Major League Baseball, joining the Brooklyn Dodgers as the game’s first black player in the modern era.

In 2017 — 70 years later — the Los Angeles Dodgers have one American black player on their roster.

Ah, progress moves in slow and mysterious ways.

As it turns out, according to a USA Today study, of 868 players on MLB rosters at the start of this season, only 62 were African Americans. Sixty-two! Heck, you could find a larger gathering of black men at an Engelbert Humperdinck concert.

American blacks constituted just 7.1 percent of Opening Day rosters, the lowest number since 1958.

I know many of my whiter friends will cut me short right here and say, “We’ve got to stop talking about race. We’ve got to get past race.” Frankly, this reminds me that most of the folks who say “money isn’t everything” are the ones who have it.

Race defines America — how could it not?

For the first 87 years of our 241-year history, we had slavery. In 1863, blacks were emancipated; then, a scant hundred years or so later — man, times flies when you’re having fundamental injustice — we passed the Civil Rights Act of 1964, essentially declaring blacks equal to whites.

That’s right: We’re so screwed up, we had to enact a law to declare that everyone should be pretty much treated the same because time and again we have proved we will discriminate.

(Speaking of which, if — in the land of liberty — you are born black, female and gay, that’s three strikes against you before you’re out of the maternity ward. It’s like starting a 100-yard dash 10 or 15 yards behind — you can never catch up.)

Racism always bubbles under the surface here. We pretend it’s not there until it obviously is.

Now, I don’t know whether racism is a factor in the decline of blacks in baseball, but the numbers are stunning: In all of MLB, there are eight black starting pitchers, no black third basemen and no black catchers.

(You’re trying to tell me, out of 43 million black people in the United States, not a single one of them can crouch like Tim McCarver and put an index finger down to call for a fastball?)

Alas, baseball is not the only profession facing a glaring absence of minorities. There are many other notable fields of American life in which blacks are greatly underrepresented:

●Electricians (5.9 percent).

●Advertising (6.6 percent).

●Aircraft pilots (3.1 percent).

●Construction managers (3.8 percent).

●White supremacist groups (0.0 percent).

Which brings us to the Adam Jones incident, in which the Orioles center fielder was called the n-word by Red Sox fans at Fenway Park last week and a bag of peanuts was thrown at him.

Racist fans in Boston? Say it ain’t so, Joe. Or, as was so famously put by Captain Renault — in “Casablanca: Faneuil Hall,” the remake of the 1942 classic “Casablanca” — as he walked into a Boston sports bar, “I am shocked — shocked — to find that bigotry is going on in here.”

(“Casablanca: Faneuil Hall” is a largely unseen, underrated gem, starring Casey Affleck as Rick, Maria Menounos as Ilsa, John Krasinski as Victor Laszlo, Bill Belichick as Major Strasser and Steven Tyler as Sam the piano player.)

In his 1979 memoir, Celtics great Bill Russell called the city “a flea market of racism.”

Longtime District sportscaster Harold Bell once told me that they were no more racist in the South than in the North; the difference, he said, was in, say, Biloxi, they wore their hearts on their sleeves while in say, Boston, they were more insidious, shaking your hand while shading their feelings.

As for Jones — not to blame the victim here — but he could have avoided the unwelcoming Fenway fans if, like most of his athletic peers, he had pursued a football or basketball career.

Or, at the very least, to distance himself from the bleacher riffraff, he should have become a catcher.

Ask The Slouch

 Q: Is it possible that your kidney stones were caused by your switch from Pabst to Yuengling? Must have been quite a shock to the body. (Kim Hemphill; South Riding)

A: My body, hardened by years of Hubie Brown the-defensive-rotation-came-late analysis, is immune to shock.

Q: With the lengthening of the televised NFL draft, is it only a matter of time before it becomes a 10-week original Netflix series? (Howard Kramer; Bethesda)

A: From your lips to Roger Goodell’s ears — official announcement expected early next month.

Q: At $495, do you consider the Lonzo Ball Z02 signature shoe a steal or a swindle? (James Schwartz; Rochester, Minn.)

A: For $495, it had better be a sneaker iPhone.

Q: Do the Cleveland Browns’ rookie contracts include vocational training for their next career? (Roger Strauss; Silver Spring)

A: Pay the man, Shirley.

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