As far as I can tell it was an Army project and horses were deemed more appropriate. The desert people kept both horses and camels. The horses were faster, the camels had more endurance. With the enemy riding horses the camel troops couldn't pursue successfully or avoid battle. Civialians didn't want them because they didn't break to harness easily, and horses could do multi-duty work, riding, pulling, etc.
Sponsored by Jefferson Davis, then Secretary of War, later President of the Confederacy. I can why he thought it worth trying, camels in the arid Southwest. When the Camel Corps was deemed unsuccessful, the army just let them go, and there were reports of feral camels for years afterwards. One turned up at Vicksburg during the Civil War:
Handy tip: If you stand a dromedary on it's tail the back makes a "D". A bactrian would make a "B". (And, as Asia is bigger, you need an extra hump to get around there.)
Happy birthday US! https://www.facebook.com/video.php?v=1558008864241439 This short is chock full of puns.