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Sad admission: About the only thing I knew about Trinidad before this morning is that Rayful Edmonds once ruled the roost there.

Now I also know a happier part of the neighborhood’s past, thanks to Brett Abrams: It’s the birthplace of interleague baseball.

Abrams is a local historian and author of “Capital Sporting Grounds: A History of Stadium and Ballpark Construction in Washington, DC.” Today he’s leading me on a tour of the city’s sports facilities, built and unbuilt, still standing and long gone.

Among the goners, but not totally forgotten, is American League Park I, once located at the corner of Trinidad Avenue and Neal Lane N.E.

At the turn of the last century, as Abrams explains things, the National League and upstart American League were feuding. The AL wanted a DC team, and opted to set up shop off Florida Avenue NE in what was then a 25-minute rail commute from downtown. The stadium site had been the location of a rock quarry owned by the Washington Brick Company, a masonry firm that a year earlier had gone out of business. (So Edmunds wasn’t the first guy making money selling rocks out of this neighborhood, it turns out.)

“Can you imagine turning a rock quarry into a baseball field, and the ditches they had to fill?” Abrams says.

They got the job done, and in 1901 a new team, the original major league club named the Washington Senators, began play there. The first game, on April 29, 1901, had the hometowners taking a 5-2 win over the Baltimore Orioles (who would end up a few years later as the New York Yankees.

The field’s dimensions were, by today’s standards, hilariously imbalanced: 295 feet to the left field fence, 555 feet to center, and 455 to right.

The stadium’s most notable contribution: Baseball’s first public address announcer gave the lineups to the American League Park crowd over a megaphone in 1901. The biggest game ever played in the park came in the spring of 1903, the team’s last season in Trinidad, when the Philadelphia Phillies of the older and richer National League traveled to DC for an exhibition.

There had been bad blood between the leagues and the teams — the Senators had signed a handful of Phillies players during their inaugural season — to that point.

According to Abrams, the Senators/Phillies tilt was momentous: “The leagues had never played each other before,” he says. “So even though it was an exhibition, it was important.”

And in this first interleague game, the American League team won.

Judging by the current Red Sox/Nats series, some things about DC baseball haven’t changed over the last century.

There used to be a ballpark here.