The making of a Niners fan starts before birth among the faithful who live on one short block of Alabama Street in the Mission District.

“Every kid here has gotten a 49ers jersey at the baby shower, whether it is a boy or a girl,” said Tracy Gallardo, as she stood in front of her home, which she explained is the dun color from Kezar Stadium because her painters could not find “49ers Gold” to go with the red trim. “We are proud of our little Alabama contingent.”

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On any game day — home or road, preseason or Super Bowl — the street draws 50 or more jersey-wearing neighbors, from grandparents down to newborns in “SF” onesies and puppies in Niners sweaters. Gallardo puts on her replica jersey, No. 22, while her husband, John, wears No. 21, but not for Matt Breida, Frank Gore or Deion Sanders. They wear these numbers to guide the flock to their block, between 21st and 22nd streets.

“It used to be way bigger,” said John Gallardo, who drew a uniformed crowd of 38 to a pregame rally Sunday afternoon, a week before the San Francisco 49ers take on the Kansas City Chiefs in Miami for Super Bowl LIV. “I’m talking 100 to 200 people before the street got gentrified.”

There are still six hardcore flag-flying Niners households on the 900 block of Alabama, and the ones who have been squeezed out of the city took their jerseys. They return for games, from as far away as Antioch and Tracy. The gentrifiers are welcome too, and so is the lone Oakland Raiders fan who defiantly flies the silver-and-black from her porch. It helps that she is married to a 49ers fan who flies his red-and-gold flag on the other side of the front door.

“All of us on the street form a family that has one interest and one goal: for the Niners to be victorious. Every game means as much as every other game,” said John Marksman.

Marksman lives in a building painted a neutral gray, but only because it is a rental. Instead, he expresses his love for his team in the living room, which he painted in fire engine red and the precise shade of “49ers Gold” that the Gallardos’ painters were unable to locate.

Marksman has an estimated 300 artifacts on display in his home, including signed helmets and programs, gold satin jackets, championship pennants and replica Super Bowl rings, flags and banners. He’s lost count of his replica jerseys, though he knows he has the rare “Team of the Century” jersey bearing the numbers 16 (Joe Montana), 33 (Roger Craig), 42 (Ronnie Lott) and 80 (Jerry Rice), in both red and white.

He also has a polished 2001 Harley-Davidson Road King, custom painted, detailed in stickers, and bearing the license plate “49er Hog,” always ready for his postgame victory tour. His neighbor, Kuko Herrera, puts a real hog in a copper pot and makes carnitas right there on the sidewalk. An hour before kickoff everybody comes out of their home and onto the street, like one massive tailgate party.

The high schools represented are O’Connell, Mission, Balboa, Washington, Lincoln, Lowell, Polytechnic, McAteer, and Star of the Sea. Sacred Heart is represented by Neil Hallinan, from the famous family of pugnacious attorneys. He grew up on the west side of town but married onto Alabama Street and wears No. 85 (George Kittle), while their 7-year-old daughter, Xochitl, wears No. 10 (Jimmy Garoppolo.)

“We’re all old school S.F.,” said Hallinan, looking up the stairs of the Gallardo home during the team photo. “That crew right there is the classic Mission District community my wife (Vanessa Peña-Hallinan) grew up in.”

Among those on the steps were two city supervisors, Shamann Walton and Ahsha Safaí. Neither one represents the Mission, but the 900 block of Alabama on a Sunday afternoon is a good place to conduct retail politics.

“It’s great to see so many people indigenous to the community,” said Walton.

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A San Francisco resident, born and bred, Walton proudly wore No. 16 (Montana) on Sunday, while Safai had to borrow a jersey. But there are always plenty of loaners — not counting the signed jerseys in frames and hung on the living room walls.

“I’ve got eight or 10 of them myself,” said Steven Gallardo, who has been wearing No. 99 (DeForest Buckner) since September because he started the NFL season with it and the Niners kept winning. This caused anxiety during road games because some of the people on the block, Gallardo’s father being one of them, are careful to wear red when the team plays at home and white when they are on the road.

Steven Gallardo does not have a white Buckner jersey so he compensated by lighting a religious candle bearing the 49ers logo 30 minutes before kickoff each game. This caused a secondary level of anxiety when the team made the playoffs and Gallardo managed to score a ticket to both home games. Down to Santa Clara he went, in his No. 99 jersey, leaving his mother in charge of the 49ers candle.

Tracy Gallardo was instructed to light it 30 minutes before kickoff and text her son the photo with a timed imprint to make sure she had done it correctly. Then he required a live FaceTime connection to prove it was still burning throughout each game. That is the level of ritual that is honored on Alabama Street.

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Another ritual is that the street suddenly empties before kickoff. The fans who still live on the block go to their own inner sanctums and those who don’t live on the block pile into the Gallardo garage, which has a TV screen, metal folding chairs and championship pennants.

Only the fans too young to follow the action stay out on the sidewalk in their jerseys and cheerleader dresses.

“We’re watching the game, watching the kids. Sometimes not watching the kids,” Tracy Gallardo said with a laugh.

If the game ends in defeat, the block grows quiet and mournful.

Marksman has season tickets but he announces any road victory by kick-starting the 49er Hog, the signal for the postgame party to commence.

“When we celebrate, we celebrate in front,” said Juliana Marquez, who is the rare outlier in that she wears a 49ers track warm-up. “I’m not a jersey girl,” she said, but her daughter Marisa Mabutas is. She is the only one who wears No. 7 for Colin Kaepernick.

No. 16 still dominates because that is what started the tradition, nearly 40 years ago, when the Niners clinched their first Super Bowl title against the Cincinnati Bengals in January 1982.

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Another Super Bowl MVP, Rice, is also heavily represented by No. 80. So is No. 52, Patrick Willis, who played in the team’s one Super Bowl defeat, versus the Baltimore Ravens in February 2013.

Marksman wears No. 33 for Craig, a sign he has forgiven the running back for the fumble that cost the team a chance at a three-peat in the 1990 season.

“We all make mistakes,” said Marksman, thrown into a momentary funk at the mere mention of the 1990 NFC Championship Game at Candlestick Park. “I can’t believe it happened, but it did.”

After Marksman revs up the 49er Hog, he rides around the block, twin flags snapping in the wind behind him and the horn blaring. By the time he is back, the sidewalk is full of red again. John Gallardo has backed his red-and-black 1962 Impala out of the garage and they are joined by a 1968 Camaro. With more flags flying, they make a second lap in formation with Marksman in the lead, to Dolores Park and back.

Then the parade begins in earnest. The foot soldiers form up in their jerseys and start the march up Alabama to 24th where a second Alabama Street contingent of 25 or so joins in.

It is like a second line in New Orleans. People they pass along the route are swept into the parade in their own jerseys and by the time they reach the intersection of 24th and Mission they are at full strength: 100 — maybe 200 — escorted by Marksman on the 49er Hog.

“Everybody is screaming and hollering,” he said, afraid to jinx his team. “It’s going to be crazy on Mission Street when the Niners win the Super Bowl.”

Sam Whiting is a San Francisco Chronicle staff writer. Email: swhiting@sfchronicle.com