Very nice chip there, Rob.
Here's my theory on that Riverside-Davis Dam chip location.
If you read the history of Laughlin, NV (Wikipedia or elsewhere), you will see the evolution of an unincorporated part of Clark County that Don Laughlin bought, then opened the Riverside Casino. Informally, the area was known as "Southpoint" or sometimes "South Pointe". When it finally got big enough, the postal system named the town "Laughlin". But during the early days, its proximity to nearby Davis Dam was noted on some of the chips and other gaming items (matchbooks, ashtrays, dice).
Bottom line, I think the Riverside-Davis Dam chip is from the same Riverside Casino that's now Laughlin. It should probably be cross-referenced that way in the Chip Guide, IMO.
For other older (pre-Laughlin, NV) casinos, look these up on the Chip Guide:
Riverside Casino (Southpoint era to today)
Nevada Club, Odie Lopp's
Nevada Club, South Point
Monte Carlo Resort (says Laughlin, but actually closed before)
Colorado River Hotel - Southpoint, Nev
Here's a pair of dice I find interesting (from Chip Guide):
Note that Odie Lopp's Nevada Club refers to its location as "Davis Dam, Southpoint, Nev."
Now my reason for the use of "Davis Dam" location on your Riverside chip:
If you look at this Google map, you'll see the bridge that Don Laughlin personally paid for that crosses from Nevada to Arizona immediately North of his Riverside Resort.
Prior to that bridge, there were only 3 ways to cross over from Nevada to Arizona -- The Hoover Dam bridge (far north of here), the crossing at Needles, CA (far south of here), or the Davis Dam bridge that still exists about 2 miles upstream from present-day Laughlin. The Davis Dam landmark would have been the logical reference for visitors from both the Nevada and Arizona sides of the river.