Westerns were one of the most popular genres in the early to mid twentieth century and the number of pulp magazines devoted to the western gives us an indication of exactly how popular. Even the venerable Black Mask in it's early years specialized in "western, detective, and stories of action."
YouTuber "bestjonbon" has compiled western covers from various pulps -- from Ace-High Magazine ("Western, Action and Sports Stories") to Zane Grey's Western, with stops in between at Big-Book Western, Cowboy Stories, Masked Rider Western, The Rio Kid Western, Thrilling Western Stories, West, and many others.
Guns blazing, horses bucking, ladies in danger, owlhoots being nasty, fists flailing, Indians attacking, cattle stampeding...it's all here. Great artwork and covers touting some of the best (and not-so-best) writers of the day.
A great gallery of covers.