For more than 100 years, the University of Kansas Jayhawks and the University of Missouri Tigers have been embroiled in a bitter rivalry.

It's a rivalry that's alive and well, even though the teams haven't played each other in two years.

RELATED: Jayhawks and Tigers Love to Hate Each Other Across State Line

Before Mizzou left the Big 12 Conference for the Southeastern Conference, the relationship would culminate in a bi-annual "Border War," where the teams met in a brutal fight for bragging rights. But the rivalry — and the team's mascots — actually date back to the Civil War.

An intimidating mythical bird

According to the University of Kansas, in the 1850s, Kansas was a battleground of “freestaters” and pro-slavery forces.

At the time, people started to refer to people across the region as jayhawkers, a combination of the blue jay, noisy and quarrelsome — and the sparrow hawk, a stealthy hunter. The nickname was meant as a warning: don’t mess with a jayhawker.

The term was used to describe both the free-state and pro-slavery forces, but eventually stuck with the “freestaters,” and when the KU football team first played in 1890, it adopted the nickname as its own.

The first illustration of the mythical Jayhawk in 1912 wore shoes for kicking opponents.

Meanwhile in Missouri ...

In the 1860s, Missouri, like Kansas, was a border state with divided loyalties. It started the war as a slave state, but as the war neared an end, the Union cause had begun to take over, according to the University.

Pro-Confederate forces launched guerrilla-style fighting against Union forces and small towns formed “home guards” to protect themselves from guerilla bands. Columbia’s militia named themselves the Missouri Tigers and when the university’s football team was formed in 1890, they adopted the Civil War defenders’ nickname.

Later, in 1984, the MU cheerleaders held a contest to name their mascot, and the Missouri tiger was officially dubbed “Truman” after famous Missourian, President Harry Truman.

This look at Missouri and Kansas is part of KCUR's months-long examination of how geographic borders affect our daily lives in Kansas City. KCUR will go Beyond Our Borders and spark a community conversation through social outreach and innovative journalism.

We will share the history of these lines, how the borders affect the current Kansas City experience and what’s being done to bridge or dissolve them. Be a source for Beyond Our Borders: Share your perspective and experiences on the state line with KCUR.