Green’s Dictionary of Slang

(US) a euph. version of god-damn adj. (1)

1885		Harper’s Mag. Aug. 400/2: You’re a goldarn liar, Balaam, and blast your old buttons, you kin walk home by yourself [DA].
1886		St Paul Dly Globe (MN) 16 Aug. 5/3: I sot thar [...] wonderin’ if the gol-darn thing wouldn’t bust.
1901		T. Hammond On Board a Whaler 198: Not by a gol darn sight.
1911		Crittenden Record-Press (Marion, KY) 2 Feb. 1/6: All this gol-darn discussin’ over tobacco, tobacco, tobacco.
1913		‘Scissor Bill’ in Lingenfelter et al. Songs of the Amer. West (1968) 547: The gol-durn Swede.
1929		E. Dahlberg Bottom Dogs 2: The cattlemen in and around Dallas all said she was sure one nice sweet little lady and that it was a gol durn shame that a pimp like that [...] should get the best of her.
1942		‘The Wids’ Song’ in C.H. Ward-Jackson Airman’s Song Book (1945) 164: Off to England we should go / To lend a hand in this goldarn show.
1991		B. Hamper Rivethead (1992) 36: I wish these goldarn fans would kick out a little more air.
2003		B. Connelly Forgetting Ireland 73: I’ve got this goldarn thing about how they neglected the Irishmen [...] from about three different sources.