Why Do Baseball Pitchers Warm Up in the Bullpen?

Watch any Major League or College Baseball game, and you’ll hear the word “bullpen” a couple dozen times. We don’t bat an eye about it now, but if you stop and think, it’s kind of a weird word to describe the waiting room for pitchers hoping to see some game time. Like other odd sports terminology, for example, the word “quarterback” in football, there’s a story behind the name.

So, what’s the origin of the bullpen?

Maybe Mad Men Invented the Bullpen

Ads have been plastered around baseball field fences since horse-drawn wagons roamed the earth. One theory of the origin of the term “bullpen” assigns the name to ads sponsored by the Bull Durham Tobacco Company.

As you might guess, an ever-present icon of the company’s brand was a large bull. So, if you imagine big signs plastered along the fences, players would be warming up “under the bull.”

While this idea has some merit, there is evidence the term “bull-pen” was used long before relief pitchers became a regular part of the game in the 1890s.

An additional bit of trivia… you’ll notice “bullpen” is both hyphenated and not in this story. That’s intentional as the use of the term evolved over the years.

Bullpens: The Cheap Seats

If you build it, they will come, even if they can’t afford regular seats.

There used to be a happy middle ground between pricey reserved seats in the stadium and the iconic knothole in the outfield fence. Areas called “bull-pens” in outfield foul territory were reserved for the really cheap seats, where impoverished fans, or those with less disposable income, were packed in like cattle. Some stadiums even allowed these bovine spectators to drift into the stadium after the first inning or so.

Over time, stadiums expanded by adding bleachers and the foul ball territory area bullpens became the area where relief pitchers warmed up—close to the action but still out of the field of play.

From the Historian’s Mouth

Last but certainly not least, as the purveyor of the final theory has impeccable street creds, is the idea that the term came from a mid-19th century game called… bull-pen.

As Major League Baseball historian John Thorn describes, the game, popular in the midwest around the 1850s, involved two teams of players, one of which surrounded an area called the “bull-pen.” The opposing team was inside, and the contest somehow involved throwing a ball. Ipso facto e. pluribus unum, the relief pitchers’ enclosed area is still called a “bullpen” to this day.

Of course, this explanation isn’t mutually exclusive with the foul territory cheap seats idea, as when relief pitchers came into vogue, they often warmed up in the same areas previously occupied by rabid fans low on funds. So, in all likelihood, since the term “bull-pen” was associated with baseball in general terms in the 1870s and with relief pitcher warm-up areas around the term of the century, the origin of today’s bullpen was somewhat evolutionary.