One of the greatest ongoing sports rivalries is in Alberta, Canada, dating back to the founding of two cities in the famous province. The bitter clash between the Calgary Flames and Edmonton Oilers is the main show. But the rivalry trickles down from political disputes and colors matchups between teams across many sports. This is how the Battle of Alberta came to be.

A clash of identities: Calgary vs. Edmonton

As the Literary Review of Canada reports, the history of the Calgary-versus-Edmonton rivalry goes back to the founding of the cities. The commerce and culture of the region is divided, quite literally, by the Battle River. Once a dividing line between Cree and Blackfoot tribes, who spent decades at war over the territory, it became the division between two large, culturally separated cities.

There is also a political divide, stemming from demographic and business differences, as Reuters reports. Edmonton historically leans left, bolstered by its presence as the first major stop en route to the Yukon gold fields. The Canadian government invested heavily in the region because of this. It encouraged a culture of support for the liberal party.

Meanwhile, Calgary is a longtime conservative stronghold. Rather than commerce, it was centered on production: large ranches filled with thousands of cattle. While Edmonton became ever more cosmopolitan, Calgary was largely left to its own devices. With little love for a government focused on the other side of the river, an entrepreneurial drive colored its emerging culture.

Sports is the most famous stage for the Battle of Alberta

The cultural and political rivalry is still present today, albeit in far more muted terms. Much of it plays out in sports. First, there’s the CFL. The Edmonton Football Team’s enmity toward the Calgary Stampeders is a strong enough rivalry to earn Battle of Alberta status for their matchups, according to CBC.

The Calgary Hitmen and Edmonton Oil Kings are junior NHL franchises. But here the rivalry plays out differently, according to WHL.ca. The Hitmen are a longtime draw, dating back to 1995. They established themselves as one of the top places to see top NHL prospects in action. The Oil Kings, on the other hand, have slowly built up clout since 2007. They have yet to encourage a similar fervor among the Edmonton hockey fandom.

One of the greatest sports rivalries is between the Oilers and Flames

It makes sense why Edmonton’s part of the Alberta rivalry is so focused on the NHL. The city played host to the greatest hockey player of all time, Wayne Gretzky. While the Oil Kings are slowly establishing their place in the city, the history of their headline hockey team is a massive draw away from them.

The Oilers are the pride of Edmonton, their NHL representative in a place where hockey fandom reaches a nearly religious fervor. It goes without saying that they find a nearly equal, and opposite reaction in Calgary, where the Flames burn bright in the hearts of the populace. It was all turned to a fever pitch for a time, leading to a spurned Flames fan base that is out for revenge decades later.

According to ESPN, the rivalry boiled over when both teams build strong postseason contenders in the 1980s, Champs or Chumps reports. By the fifth and final time the brutal rivals met in the NHL’s Division Finals in 1991, the Oilers had dominated their meetings 4-1. Several of these games went down to the wire, with three coming down to a seventh and final game.