It is rare for teams from one market to play in the Stanley Cup and N.B.A. Finals in the same year, and a first for southern franchises, but it was bound to happen.Martin Schwartz and Matthew Mandel are having a moment. Actually two. The lifelong friends hit the sports jackpot this month when the Miami Heat and Florida Panthers both ran the playoff gauntlet and made it to the finals, where they are now vying for N.B.A. and N.H.L. titles simultaneously.Schwartz and Mandel, lifelong South Florida residents and friends since college, have shared season tickets to both teams for years. They have had lean years — the Heat won just 15 games in the 2007-08 season — and home games filled with noisy fans rooting for the visiting teams.They celebrated the Heat’s title runs in 2012 and 2013 powered by Dwyane Wade and LeBron James and savored the Panthers’ sporadic playoff runs. But never did they believe both teams would start the postseason as No. 8 seeds, topple top-ranked clubs in upset after upset and battle for championships.“I was very pessimistic when the playoffs began,” said Schwartz, who was a batboy for the Florida Marlins in the 1990s and wore a Panthers jersey to the Heat game on Wednesday when they fell to the Denver Nuggets. “But we’ve come to realize it’s all about the playoffs. You gotta enjoy it. You only get one chance.”This is the 10th time that two teams from one market have played in the Stanley Cup and N.B.A. Finals in the same year. The last time it happened was in 2016, when the Golden State Warriors and San Jose Sharks (both losers) vied for titles. The Bruins and Celtics have done it three times, stretching back to 1957 and the Knicks and Rangers twice. But never have a region’s hockey and basketball teams won in the same year.Panthers fan Carissa Kania.Saul Martinez for The New York TimesAnthony Rowell opts for a helmet instead of a toque.Saul Martinez for The New York TimesKC Navarro reps the Miami Heat.Saul Martinez for The New York TimesEmma Uzzo has got the Panthers.Saul Martinez for The New York TimesThe chase for championships has turned into a nightly affair in South Florida this week as the Heat and Panthers play four consecutive nights at home. Their arenas are about 40 miles apart, and each team has their core fans, though some like Schwartz and Mandel have gone all in on both sports. The teams are both down 1-2 in their series heading into Friday’s Heat game.“It almost never happens, so we wanted to give it a shot,” said Raul Arias, a Miami native who attended the Heat and Panthers’ games on back-to-back nights with his brother, father and friend.This is the first time that two teams in a Southern market have chased titles at the same time, but it was bound to happen. The country’s biggest sports leagues have been pushing into Florida for years, and for good reason: They are businesses in search of new fans, new sponsors and more television viewers, and America’s demographics have been tilting South and West for decades.The Rangers and Bruins have been on the ice since Calvin Coolidge was president. But history is fungible and in sports, fleeting. The Heat arrived in Miami in 1988, back when Bobby McFerrin’s “Don’t Worry, Be Happy” was a hit song. The Panthers entered the N.H.L. in 1993. Since then, six teams — the Columbus Blue Jackets, Winnipeg Jets, Nashville Predators, Minnesota Wild, Seattle Kraken and Las Vegas Golden Knights — have joined the league.Fans at Quarterdeck Restaurant near the Panthers arena for Game 3.Saul Martinez for The New York TimesThese South Florida hockey fans could easily hang with their northern counterparts.Saul Martinez for The New York TimesThe Final between the Panthers and Las Vegas Golden Knights is, perhaps to the dismay of more traditional fans in Canada and the northern states, the ultimate distillation of the N.H.L. Commissioner Gary Bettman’s “Southern Strategy.” Bettman has defended this shift despite the financial woes of teams in Arizona and other new markets. But teams in northern markets, including the Devils and Islanders, have had financial problems. And while teams in Southern markets — Atlanta comes to mind — have lost teams, the Tampa Bay Lightning and Dallas Stars are both on solid ground.Speaking to reporters before the first game of the Final, Bettman’s deputy, Bill Daly, noted that Ryan Smith, the owner of the Utah Jazz, has also expressed interest in bringing a hockey team to Salt Lake City.Fans of older teams might groan if another team landed in a “nontraditional” hockey market. They already think little of South Florida fans, who are accused of showing up fashionably late to games and leaving early to beat the traffic. They’re often typecast as transplants who still root for old hometown teams. Or the ultimate burn: They just show up when the going’s good and disappear when their teams are in the tank.Miami Heat fans and siblings Federico, Jose Luis and Luis Benitez before the start of Game 3.Saul Martinez for The New York TimesAll of that’s true to some degree. But fans are like that everywhere, including in New York and Los Angeles. And while Florida has been growing by leaps and bounds, adding millions of new residents in the past decade, some of the transplants here are embracing their newfound sports bounty. The playoff games have been sold out with some tickets on the resale market fetching four figures. Since May 1, sales of Heat and Panthers gear have soared 460 percent compared to the same period last year, according to Fanatics. Sports radio hosts have been yapping hoops and hockey, with some soccer spliced in after Lionel Messi said Thursday he was joining Inter Miami.“The more they win, the busier we get,” said Norma Shelow, who for more than 30 years has co-owned Mike’s at the Venetia, a short walk from the Kaseya Center. She said business is up 40 to 50 percent during the playoffs, when fans start filling the restaurant a couple hours before game time. Since May 1, sales of Heat and Panthers gear have soared 460 percent compared to the same period last year, according to Fanatics.Saul Martinez for The New York TimesShelow said she had plenty of regulars, including N.B.A. referees who stop by after games. But she also welcomes lots of newcomers, who typically call for reservations even though the bar is first-come, first-served.“I’ve lived here all these years and never seen this,” said Abel Sanchez, 50, an amateur sports historian. “If either of them wins a title, it’s a moment. If both win, who has the movie rights? And if you want to hop on the bandwagon, there’s room.”It’s not unusual for transplants to adopt a new home team, or to split their loyalties. My dad rooted for the baseball Giants growing up in New York, then switched his allegiance to the Mets when our family decamped to Long Island in the 1960s. (He still loved Willie Mays and took me to see the San Francisco Giants when they came to town). When he moved to West Palm Beach in the 1990s, he adopted the Marlins, who rewarded his loyalty with two World Series titles.Florida added four million new residents in the past decade or so, and some were bound to become Panthers fans.Saul Martinez for The New York TimesFlorida added four million new residents in the past decade or so, including many flocking to Miami from Latin and South America. Some of these newcomers have adopted the Heat and Panthers as their home teams even if they never played basketball or hockey. And why not? Rooting for a sports team may be the most communal activity in American life.“I’m all in on Jimmy Butler,” said Adam Trowles, a Briton who splits his time between Miami and London, where he watches Heat games in the wee hours. “I’d marry him if I could.”On Wednesday, Trowles looked for tickets to attend game three against the Denver Nuggets. The cost was too steep, so he and his girlfriend, Gessica Jean, watched the game at Duffy’s Tavern in Coral Gables.For all the hoopla, football remains the undisputed king of sports in Florida. The Dolphins and the Miami Hurricanes are still the toast of the town — when they win. Tampa went wild in 2021 when the Buccaneers won the Super Bowl and the Lightning won the Stanley Cup.But basketball and hockey have their place. Transplants from Canada and the Northeast and Upper Midwest have held on to their allegiances. But over time, new fans are born, even for the Panthers, whose home ice at the FLA Live Arena, in Sunrise, Fla., is sandwiched between a shopping mall and the Everglades Wildlife Management Area. For locals, it’s been a parade of riches.At Quarterdeck, a sports bar 10 minutes from the arena, Tyler Craig watched the Panthers beat the Knights in overtime on Thursday.“It’s almost exhausting how many games we’ve been watching,” he said. More