His final show is Wednesday, but the local legend got his start in broadcasting when he was a student at Ball State University.
Letterman parlayed his stint on a Ball State student radio station into a career as America's Late Night talk show funnyman.
"Some people say I am the first guy to hire him and the first guy to fire him," says Al Rent, who worked as Student Program Director at the campus radio station when he was a junior.
Rent had to reassign Letterman after the freshman started altering the biographies of classic composers.
WATCH: WTHR pays tribute to David Letterman
"He had a little gleam in his eye and then he would look directly at you, but then he would look away and when he looked away that was the cue that you had been had," Rent laughingly remarked.
Letterman donated his name for the new communication building. He donated the money behind a high-profile lecture series and continues to fund scholarships to budding broadcasting students.
We asked some Ball State students what they thought of when they think of David Letterman.
"You can come from a small Midwestern-city and make it huge. That is what is really cool. He represents how far we can go," the first male student responded.
"To all the C students before and after me," another added, referring to a Letterman plaque that is currently on display in the communications department.
"A lot of late nights hearing my parents busting up. A lot of laughter coming from the living room," another student remembered.
"I know a lot about Letterman," one girl added. Did he have anything to do with why you came here, we asked? "Yes, I came for the TV program. I want to go into late night television," she concluded.
How fitting - but Letterman's love for Ball State cut both ways, like when he highlighted the school's long football losing streak but then reveled when the school finally scored a victory.
"He put the Ball State cap on several times. People definitely connect him to Ball State which is great for us," Roger Lavery, Dean of Ball State's College of Communication and Media.
Now Lavery hopes Ball State might be able to capitalize on Letterman's future.
"In addition to the lecture series we've had conversations with his attorney agent about whether or not some of his memorabilia be displayed here in the Letterman building as part of the Letterman collection. We'll see how it goes. Obviously they are busy getting his last show out of the way but after that I am hoping we have a permanent collection. We already have the art museum curator exhibit designer help us find a location and came up with a design so we will just see," Lavery said.
Needless to say, the great run for Letterman was also a great run for Ball State.
"We just sit back and enjoyed the benefits that came to us," Rent, who works in the Community Relations Department at Ball State, added.
Those benefits include increased enrollment and publicity. It all started with making up his own biographies for the classic composers.
In celebration of the Indianapolis native's career in broadcast news and entertainment, Mayor Greg Ballard has declared Wednesday David Letterman Day in the city.
