Upward of 25,000 scraps of paper and yellowed newspaper clippings in Peter Gorton’s northeast Minneapolis basement tell dual stories that intersect at an improbable place: the central Minnesota town of Bertha.

That mountain of research chronicles the dominant but largely forgotten career of a black baseball pitcher named John Wesley Donaldson. The other plot line centers on Gorton, a 46-year-old speech consultant and tireless researcher.

For 14 years, Gorton has been on a mission to rekindle the legacy of Donaldson, who crisscrossed Minnesota from 1911 to the 1920s between stints in the Negro leagues and with several barnstorming teams.

Gorton’s goal is to get the southpaw enshrined in the National Baseball Hall of Fame in Cooperstown, N.Y., which plans to pluck more historic black players from obscurity in 2020.

Nicknamed “Cannonball,” Donaldson played baseball for 34 years before becoming the game’s first African-American scout for the Chicago White Sox in 1949. He spent the peak of his career in Minnesota, playing in scores of towns from Worthington to Hibbing.

Gorton and his volunteer army of baseball researchers not only have documented 399 victories and at least 4,980 strikeouts for Donaldson, they’ve pinpointed 130 Minnesota cities and towns where he pitched.

One was Bertha, where Donaldson spent the 1924, 1925 and 1927 seasons with the Fishermen. “It’s swamp country without a fishing lake around,” Gorton said. “But the team was named after Ernie Fisher, the team’s general manager.”

Gorton knows the terrain well. He grew up 20 miles northeast of Bertha in Staples, where his dad was a dentist. In 2002, a phone call from an old social studies teacher “started a journey for me,” he said.

That teacher, Steve Hoffbeck, was writing a book about black baseball players in Minnesota and asked Gorton if he would take a stab at researching Donaldson. So Gorton made a trek to Bertha and stopped at the town’s historical society.

He found a poster of Donaldson from the 1920s and a basketball program from 1988 featuring Gorton and his Staples High School teammates. “I thought, goodness gracious, this guy is meant to become important to me,” he said.

His passion to unearth Donaldson’s past only grew when 39 seconds of rare film footage of the pitcher on the mound surfaced in Fergus Falls (vimeo.com/173608869). “The 39 seconds of film showing him pitching is so vital because it proves to the YouTube generation how dominating he was,” Gorton said.

That discovery came just after his first attempt to get Donaldson into the Hall of Fame fell short in 2006. Back then, Gorton’s research team had documented some 150 victories for Donaldson.

Gorton since has scoured digital newspaper archives on the web and scanned more than 5,000 microfilm rolls to confirm that Donaldson’s actual victories and strikeouts would put him in the top ranks of big league pitchers.

Even before the footage was unearthed, newspaper clippings told the story. In 1927, the Fairmont (Minn.) Daily Sentinel wrote: “John Donaldson is — and there is no one that is qualified to speak authoritatively that will dispute it — the greatest colored baseball player of today and of all time.”

The Lake Wilson Pilot in southwestern Minnesota described Donaldson as “graceful, polished and classy. … He was the poetry and rhythm of baseball.”

And in his autobiography, Negro League legend Buck O’Neil compared Donaldson to Hall of Famer Satchel Paige. “John Donaldson … showed Satchel the way, and the fact is, there are many people who saw them both who say John Donaldson was just as good as Satchel,” O’Neil wrote.

Playing baseball before Jackie Robinson broke the color barrier in 1947 wasn’t glamorous for black players. But Donaldson was a pioneer.

One owner offered him $10,000 in 1917, he said, to “go to Cuba, change my name and let him take me into this country as a Cuban.” But Donaldson said that “would have meant renouncing my family … or to have anything to do with colored people.” He refused.

“I keep my body and mind clean. And yet when I go out there to play baseball it is not unusual to hear some fan cry out” a racial epithet, he said. “That hurts. For I have no recourse. I am getting paid, I suppose, to take that.

“But why should fans become personal? If I act the part of a gentleman, am I not entitled to a little respect?”

Born in 1891 in Glasgow, Mo., Donaldson married Eleanor Watson in 1917. She had family in Minneapolis, so Bertha was only a train ride away. The couple had no children, and when Donaldson died in Chicago in 1970 at age 79 he was buried in an unmarked grave with no one to pay for a tombstone.

Gorton helped to rectify that, along with a group called the Negro Leagues Baseball Grave Marker Project. In 2004, with help from Chicago White Sox owner Jerry Reinsdorf, former major league manager Don Zimmer and others, Donaldson got his tombstone.

But Gorton wasn’t finished. He doesn’t plan to rest until Donaldson is enshrined in the Hall of Fame. His group’s website — johndonaldson.bravehost.com — is a comprehensive collection of game stats, photos and stories under the slogan “Always Looking.”

“What started as an obsession has turned into a sense of responsibility,” Gorton said. “When you learn how great a player this man was, how can you sleep without trying to restore the legacy of a guy who deserves for people to know who he is?”

Curt Brown’s tales about Minnesota history appear each Sunday. Readers can send him ideas and suggestions at mnhistory@startribune.com.His e-book “Frozen in History” is available at startribune.com/ebooks.