The Wild West *WASN'T* in color. Don't you know anything? Back in the old days, everything was actually in black and white. Color hadn't been invented yet. Even when I was young, color was still considered a novelty and most things were still in black and white. The addition of color to westerns is actually one of those concessions to modern viewers, much like sounds-in-space. The real thing would have been in black and white.
Further proof of Pescado's factoid is that Mighty Mouse was Black and White. He was REAL. Howdy Doody, however, was a poser (He PRETENDED to be a cowboy, too!).