We need more information with this lookout. The Kresek inventory reports of a tower in the 1930s. I was able to find a trip report in the Mountaineers annual from 1948 about a visit to the High Point Lookout. This is most likely Canyon lookout although Tiger Mountain is in the region. The trip report just talking about a visit to Issaquah Mountain and reaching a tower, then calling it High Point Lookout when stating the next group up in the following month went there.

Although much of Grand Ridge is now a County Park, this is the highest point on Grand Ridge which is definitely private property. There is a road to the top, or at least within feet of the summit. Several homes are on top with one particular looking like it holds the highest point. Interestingly, the home looks like a benchmark, the home has a circular awning around the entire home, which is also circular in shape. The benchmark placed at the summit was not until 1973 so it is of no help. A 1979 USGS party said the complete benchmark station was going to be destroyed by the construction of a home. A 1944 aerial shows a road to the summit but a forest canopy makes seeing a tower too difficult.
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Canyon Lookout Site ( maybe High Point L.O.)

Distance: Drive-up
Summit Elevation: 1,422 feet
Prominence: 892 feet
Access: Paved/Private
Access:
The Basement
The road up is straightforward if you print the map. What needs to be said is that the road is marked as a private drive and no trespassing signs are encountered. Still, there are no gates and there is some room to do a U-turn at the summit where the road ends at three driveways that go in different directions. The road becomes private at a sign that says End of County Maintenance. The road actually gets better the higher you go. The homes below are older homesteads where the few at the top are much newer home sites.
grand ridge map grand ridge grand ridge
Aerial view of the final switchback to the summit area
The turn-around area is the diamond spot on the right side of the picture
Topographical Map of the area
Former Lookouts
usgs high point lookout 1936 metsker
1948 Mountaineers Trip Reports
1936 land ownership
1953 USGS, 1956 update shows homes along the road and one large something at the summit