Howdy Doody, an early show which premiered in 1947 on NBC, was one of the first.
From the en.wikipedia.org
Howdy ya'll, time for another Collaboration of the Week from WikiProject Oregon.
From the en.wikipedia.org
And boy, howdy, does Peter Oyloe's Williams deliver the twangy-and-tortured goods.
From the orlandosentinel.com
Howdy Zoo, yes the tiny creature on the computer screen may have been a booklouse.
From the en.wikipedia.org
And, boy howdy, wouldn't it be fun to watch a football game with him sometime?
From the kansas.com
Neighbor, if you're reading this, it's not too late to come by and say howdy.
From the newsobserver.com
Howdy, I recently made a wiki page for a band I like called Hidden Hospitals.
From the en.wikipedia.org
Howdy folks, its time for this week's edition of Oregon's Collaboration of the Week.
From the en.wikipedia.org
Howdy was imprisoned in Kampala prison until the high court heard his case.
From the en.wikipedia.org
More examples
Hello: an expression of greeting; "every morning they exchanged polite hellos"
Howdy! is the seventh album by British alternative rock band Teenage Fanclub, released in 2000, and the band's only album with a major sublabel.
A wife, a midwife; An informal greeting
And Hidy, "The welcome bears", two polar bears representing Western Canadian hospitality. The bear siblings were the first dual mascots in the Olympic Games. The Calgary Zoo sponsored a contest to name the bears. ...
I usually only use it if I am trying to be funny by sounding "stereotypically Texan" to my friends who are not from Texas