It was inevitable that the very zeal with which the wolf was hunted would eventually result in the trade quickly becoming obsolete itself. Extermination of the species had been the aim from the beginning. That the wolf survived as long as it did in the face of such relentless persecution may have been due to the not uncommon practice of trappers killing wolf pups but deliberately sparing the mother in order to let her breed again the next year.
After the government put into action specific programs to eliminate the wolf the hunting and killing of wolves became much more methodical and efficient. Between 1915 and the program’s eventual disbandment in 1942, U.S. government hunters killed over 24, 132 wolves.
An insight into typical attitudes of wolf hunters in the early 20th century can be found in A. R. Harding’s 1909 book Wolf and Coyote Trapping, which you can read online here.