Some rivalries are born over night, like when Hug High School had much of its student body ripped away when North Valleys opened in 2001.
Others come and go like the Reno-Sparks matchup that began in the early 1900s, but the border schools haven't played in more than five years and may never be on the same field again after the Railroaders dropped a class.
The Nevada-UNLV rivalry is probably the most hyped in the state and boasts the heaviest trophy in college football, the Fremont Cannon. But that contest has just 35 games to its history and only dates back to 1969.
The one clash that has stood the sands of time is Carson-Douglas. It started in 1923 and has since seen 67 contests, in which Carson leads the series 43-21-3. Perhaps none will be more important, or more anticipated, than Thursday's (7 p.m. kickoff) in which the Sierra League title will be up for grabs.
"First of all, and this is just based on the fact that I've had an opportunity to coach at a different school, this is without a doubt the biggest rivalry in Nevada in terms of a sports contest," said Carson coach Blair Roman, who played for Douglas in the mid-80s and was North Valleys' first football coach. "The history behind it ... you've got generations of dads and family members that have played in this game and still talk about it.
"Not only in the competitive aspect, but just the historical aspect. I mean Carson High being the oldest high school in Nevada in 1874 being established and the long tradition of Douglas, it's a really neat situation. You don't see that in a lot of places and when we do see it, it's like the rivalry that we have, it's very special. And I would categorize our rivalry as being a very special rivalry."
The two schools are separated by just 16 miles, but the memories of those contests stretches further.
The rivalry has been called off twice between 1925-1933 when Douglas' football team was defunct and a 12-year span between 1967-1978 when the two were in separate classes.
Figures have crossed borders to find coaching jobs (current Carson coach Blair Roman and Carson athletic director and former head coach Bob Bateman).
The game was even once played on a neutral field, in 2006 when Douglas installed synthetic turf and was forced to play Carson at Bishop Manogue.
The rivalry has meant something from the beginning, when Carson destroyed Douglas 76-6, the Tigers' second-worst loss of the season. The Tigers lost their first game of the year, which was also their first-ever game 102-0 to Fallon. Douglas won its first game in the series 24-0 in 1938 and followed that up with a 13-0 win later that season.
The matchup has been decided by seven points or less 20 times, eight points twice and gone to overtime twice. In games decided by 7 points or less, Carson has won 14 times.
Some games, much like Thursday's, have meant more than others though. Carson took a 13-10 overtime game in 1998 that saved it from having to travel 4 1/2 hours for a first-round playoff game.
"In '98 when we were playing them, we were playing them for essentially a home playoff game," said Francisco Vega, who now coaches at Carson. "The winner of the game would get a home playoff game and the loser would have to travel to Elko. That kind of brought some extra pressure to the game, than normal."
It's not like the game needs any extra pressure. Roman was on the losing end of two games during his junior and senior seasons in what he says were two of the most intense games he had ever played.
"As a player, we had two really tough games and we lost both of them," Roman said. "Just the intensity of both of them was by far the most intense that I played in in high school. The physical play, the hitting, just the overall emotion of it doesn't compare."
The roles, though, have been flipped now that Roman is on sideline.
"As a coach, to be honest with you, is trying to get your players to focus on the actual game and not just the rivalry," he said. "That's the biggest challenge and I can tell you as a head coach, that is a major challenge. Cause you've still got to go win it on the field and you've got to play well. That's how we're going to try and focus on it this year too."
Roman, who was Rippee's first quarterback after he took over the reigns of the Douglas program in 1985, lost back to back games to Carson in 1985-1986. The losses were in the middle of what would be a six-game winning streak for the Senators in the series.
Douglas is the team currently on a winning streak, having won the last seven dating back to 2002. Carson owns the longest winning streak in the series with 12 between 1951-1980.
"Both teams have been well coached over the years and I know coach Rippee does a good job down there," Vega said of the losing streak. "I think it's just a swing in talent is what it comes down to. For a few years there had some pretty good talent with Coach Rippee's son (Luke) and a few other players."