Early life and career
Letterman was born in
Indianapolis, Indiana. His father, Harry Joseph Letterman (April 15, 1915 – February 13, 1973),
 was a florist.
 His mother,
Dorothy Marie Mengering (née Hofert; July 18, 1921 – April 11, 2017),
 a church secretary for the Second Presbyterian Church of Indianapolis, was an occasional figure on Letterman's show, usually at holidays and birthdays.
He lived on the north side of Indianapolis (
Broad Ripple area), not far from
Speedway, Indiana, and the
Indianapolis Motor Speedway; and he enjoyed collecting model cars, including racers.
 In 2000, he told an interviewer for
Esquire that, while growing up, he admired his father's ability to tell jokes and be the life of the party. Harry Joseph Letterman survived a heart attack at age 36, when David was a young boy. The fear of losing his father was constantly with Letterman as he grew up.
 The elder Letterman died of a second heart attack
 at age 57.
Letterman's association with Ball State University was recognized by a renaming ceremony for their David Letterman Communication and Media Building in 2006.
Letterman attended his hometown's
Broad Ripple High School at the same time as
Marilyn Tucker (future wife of
Dan Quayle) and worked as a stock boy at the local Atlas Supermarket.
 According to the Ball State Daily News, he originally had wanted to attend
Indiana University, but his
grades were not good enough, so he instead attended
Ball State University, in
 He is a member of the
Sigma Chi fraternity, and he graduated in 1969 from what was then the Department of Radio and Television. A self-described average student, Letterman later endowed a scholarship for what he called "C students" at Ball State.
Though he registered for the draft and passed his physical after graduating from college, he was not drafted for service in
Vietnam because of receiving a
draft lottery number of 346 (out of 366).
Letterman began his broadcasting career as an announcer and newscaster at the college's student-run radio station—
WBST—a 10-watt campus station which now is part of
Indiana Public Radio.
 He was fired for treating classical music with irreverence.
 He then became involved with the founding of another campus station—WAGO-AM 570 (now
Paul Dixon, host of the
Paul Dixon Show, a Cincinnati-based talk show also shown in Indianapolis while he was growing up, for inspiring his choice of career:
I was just out of college [in 1969], and I really didn't know what I wanted to do. And then all of a sudden I saw him doing it [on TV]. And I thought: That's really what I want to do!
Letterman began his career as a radio talk show host on
WNTS (AM) and on Indianapolis television station WLWI (which changed its call sign to
WTHR in 1976) as an anchor and
weatherman. He received some attention for his unpredictable on-air behavior, which included congratulating a
tropical storm for being upgraded to a
hurricane and predicting
hail stones "the size of canned hams."
 He would also occasionally report the weather and the day's very high and low temps for fictitious cities ("Eight inches of snow in Bingree and surrounding areas") while on another occasion saying that a state border had been erased when a satellite map accidentally omitted the state border between Indiana and Ohio, attributing it to dirty political dealings. ("The higher-ups have removed the border between Indiana and Ohio making it one giant state. Personally, I'm against it. I don't know what to do about it.")
 He also starred in a local kiddie show, made wisecracks as host of a late night TV show called "Freeze-Dried Movies" (he once acted out a scene from
Godzilla using plastic dinosaurs), and hosted a talk show that aired early on Saturday mornings called Clover Power,
 in which he interviewed
4-H members about their projects.
In 1971 Letterman appeared as a pit road reporter for
ABC Sports' tape-delayed coverage of the
 Letterman was initially introduced as
Chris Economaki, although this was corrected at the end of the interview. Letterman interviewed
Mario Andretti, who had just crashed out of the race.
Move to Los Angeles
Letterman's comedic career took hold at Los Angeles'
In 1975, encouraged by his then-wife Michelle and several of his
Sigma Chi fraternity brothers, Letterman moved to Los Angeles, California, with hope of becoming a comedy writer.
 He and Michelle packed their belongings in his pickup truck and headed west.
 As of 2012, he still owned the truck.
 In Los Angeles, he began performing comedy at
The Comedy Store.
Jimmie Walker saw him on stage; with an endorsement from
George Miller, Letterman joined a group of comedians whom Walker hired to write jokes for his stand-up act, a group that at various times would also include
Jack Handey, and
By the summer of 1977, Letterman was a writer and regular on the six-week summer series The
Starland Vocal Band Show, broadcast on
 He hosted a 1977 pilot for a game show entitled The Riddlers
 (that was never picked up), and co-starred in the
Barry Levinson-produced comedy special
Peeping Times that aired in January 1978. Later that year, Letterman was a cast member on
Mary Tyler Moore's variety show,
 Letterman made a guest appearance on
Mork & Mindy (as a parody of
 and appearances on game shows such as
The $20,000 Pyramid,
The Gong Show,
Liar's Club, as well as the Canadian cooking show
Celebrity Cooks (November 1977), talk shows such as
90 Minutes Live (February 24
 and April 14, 1978),
The Mike Douglas Show (April 3, 1979 and February 7, 1980). He was also
screen tested for the lead role in the 1980 film
Airplane!, a role that eventually went to
His dry, sarcastic humor caught the attention of scouts for
The Tonight Show Starring Johnny Carson, and Letterman was soon a regular guest on the show. Letterman became a favorite of Carson and was a regular guest host for the show beginning in 1978. Letterman credits Carson as the person who influenced his career the most.