Per Google:

In 1991, Silver City became a smoke free casino. After losing revenue from this decision, Silver City reinstituted smoking. In mid-1999, Circus Circus announced that they will be closing the Silver City on October 31, 1999.

As I recall, they were non-smoking for a few years. Later, when the National Finals Rodeo was in town, Silver City "temporarily" reinstated smoking. I don't think they ever went back to being non-smoking.