How does a state with the fifth-smallest population in the United States produce Sunday's showdown between South Dakota and South Dakota State (ESPN+, 2 p.m. ET)? How does a state with fewer people than the city of Jacksonville, Florida, produce the top two teams in the espnW mid-major rankings: South Dakota, at No. 1 after wins against Missouri and Iowa State, and South Dakota State, close on the heels of its Summit League rival after pushing Baylor and Oregon?
Sunday's matinee might not remake the S-curve in the NCAA tournament bracket, but it features two teams that none of the favorites wants to see coming to town in March. South Dakota and South Dakota State are two teams any basketball fan will enjoy watching in February.
South Dakota has a population of roughly 870,000 -- but the math doesn't work. Maine, Montana and Rhode Island don't do this. All have larger populations. For that matter, New York and Pennsylvania might struggle to match South Dakota's top two teams.
Forget population. Focus on the populace. Then maybe Sunday begins to make sense.
Perhaps start with the Duffy sisters, who grew up in Rapid City in the state's Black Hills region. Five sisters -- enough to put their own team on the court or fuel their own dynasty.
Ciara Duffy -- the fifth of eight siblings in all and the third-oldest daughter -- first watched her older brothers play basketball during the long winter months. Then she saw sisters Caitlin and Moira play for St. Thomas More High School. She saw them win the school's first state title together. Five more titles followed, almost all with a Duffy on the court.
"That was the first time I had seen higher-level girls basketball," Ciara said of her older sisters. "And then seeing my two older sisters go on and play in college, it was kind of eye-opening. It was suddenly like I could use this thing that I love, this game that I love playing, to go to different places and get to experience all these incredible things and meet these new people."
Caitlin played at South Dakota after a season at Colorado State, and Moira played at the University of Sioux Falls, a Division II school in the state. (Younger sister Aislin is a freshman at Augustana University, another Division II school in Sioux Falls.) Ciara followed their lead, sharing time on the court at South Dakota with Caitlin for one season and now leading the team on her own.
A 6-foot-1 player who has played every role from point guard to post in a largely position-less system, Ciara might now be the best player most fans have never seen. They would be well advised to remedy that on Sunday. In the first meeting between the Summit League rivals this season, a 105-98 double-overtime South Dakota win, Duffy totaled 28 points, nine rebounds and seven assists in 49 minutes.
There aren't many players with her Swiss Army Knife array of skills. There aren't many families that produce four (and counting) daughters who play college basketball.
Yet the state has so many similar stories. It started in Rapid City for the Duffys. For South Dakota State star Macy Miller, it was Mitchell, South Dakota. It was Letcher, South Dakota, for rising Jack standout Myah Selland.
While their neighbors to the north once ruled Division II -- North Dakota and North Dakota State won a combined eight national championships in the 1990s -- South Dakota and South Dakota State had success at that level. Both then adapted well to Division I, with South Dakota State an NCAA tournament regular the past decade and South Dakota the WNIT champion in 2016.
There was ample talent for the programs to be consistently good -- and often excellent.
Ciara was right that the game could take her places. With a 4.0 GPA and an academic focus in political science and history at South Dakota, she studied abroad in Russia this past summer. But where she is from matters to her. It mattered to see South Dakota ranked in the Top 25. It mattered to get the text from Caitlin with words of praise for carrying on the program's legacy.
"I think depending on where you go, people don't even know where South Dakota is. Some people still think we ride in horse-drawn carriages to school," Duffy said. "But I think most people think it's pretty small and don't really know what goes on here.
"I think it's kind of cool, too, because sometimes those bigger teams come in here, and they're sort of surprised with South Dakota in general. We're kind of a hidden gem."
But not hidden Sunday.