21-Aug-2017 -- We were in Salem, OR for the Great American Eclipse of 2017. Since we were so close to a so reasonably available confluence point, we decided to visit. We didn't do so actually during the eclipse, unfortunately, but it was the same day.
As others have noted, the confluence point is on an onramp from exit 260 to southbound Interstate 5. From the stoplight one turns onto the onramp, then proceeds over a short bridge and the confluence point is on the left edge of the onramp lane a few yards before the merge onto the interstate.