The earliest sitcom that I have been able to track down is Mary Kay and Johnny (http://us.imdb.com/Title?0128883) which debuted in 1947. Could this be the earliest sitcom ever? I have found earlier comedy shows, but they seem to be more variety-type like "The Carol Burnett Show" was.

Maybe "I Love Lucy", but I'm not sure when that debuted, though. It was on the radion before tv was invented!

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Thurston: Now the first thing you use, darling, is your driver.
Lovey: My driver? Don't be silly, darling, you know our chauffeur is back home. I believe his name was Charles, wasn't it?
Thurston: No, darling, I'm talking about clubs.
Lovey: Of course, he drove us to all the very best clubs.
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Well, "I Love Lucy" debuted in 1951. It did not previously appear on radio. Ms. Ball did star in the radio sitcom "My Favorite Husband", which ran from 1948 to 1950 on CBS.

Nipkow patented his television system in 1884. The first commercial radio station, KDKA, began operations on Nov 2, 1920. This makes it pretty hard for any radio sitcom to precede the invention of television. Still,
commercial broadcasts of television didn't start in the US until 1939 and TV didn't really takeoff until 1946 when the wartime restrictions on building TV's were lifted.

Clearly there were radio sitcoms long before there were television sitcoms. So I guess I do need to clarify that I am looking for the first television sitcom.

I know this answer is 20 years too late but I think MARY KAYE & JOHNNY WAS the first sitcom.

What is considered the first television season? There has been broadcast TV since the 1930’s but nothing formalized until after WWII. I consider 1946 to be the first TV season.

In what year was there TV broadcasting at least 16 hours a day? I am old enough to remember TV stations signing off around midnight until 6 am. 24 hour TV wasn’t really a thing until the 1980’s although I am sure some stations did have all night programming “The late late late movie”.

Mary Kay And Johnny was the first American sitcom, the British sitcom Pinwright's Progress predates it by a year (1946)

Speaking of radio shows, are there any links to hear radio programs? It might be fun to listen to a show and picture the situation.

Mary Kay And Johnny was the first American sitcom, the British sitcom Pinwright's Progress predates it by a year (1946)

The Johnny of Mark Kay and Johnny, John Stearns would later go on to host the farm series Agriculture USA (later shortened to AG-USA). It would air Saturdays in New York on WNBC-TV.

Speaking of radio shows, are there any links to hear radio programs? It might be fun to listen to a show and picture the situation.

YouTube and the Internet archive. My father enjoys listening to The Father Knows Best radio program. I think nearly all of the old radio programs are in the public domain.