Well, the primary reason you'd expect a higher than average rate in Nevada is Casinos. Without that, Vegas would have an average rate - plus, is Casinos are the main social outlet, those who don't go to Casinos might not go anywhere and be less likely to get the virus.
My Vegas-resident brother-in-law loved counting cards and betting on unpopular baseball teams, both of which involved entering casinos. Perhaps data is better than our two anecdotes?
Google mobility reports[1] show workplaces down 55% and retail and recreation down 47% for Clark County, Nevada (where Las Vegas is), and both dropped very quickly from March 13.