It's a mixture of watching episodes, searching the internet for information, and looking over maps (both current and historic). I'd like to give a special mention to one of the sources: HazzardNet member Wekke. I had planned to link to his website and the thread about his visit to some of the locations over on cglfc.com, but in the last couple of months his website has disappeared and just in the last couple of weeks the pictures on cglfc have also gone (the thread is still there, but not much use without pictures). The location of the intersection of East Potrero Road/Highway 23 (above) and that of the first picture below are thanks to Wekke. With Wekke's pictures apparently unavailable, I may add some pictures of West Potrero Road soon. Still on Highway 23, and about 1/4 of a mile south of Lake Eleanor is this section of road with the distinctive rocky outcrop in the background. It's used in several episodes - this is from 'Uncle Boss'. Click here for a Google Maps Street View. Slightly further south is the intersection of Decker Canyon Road and East Carlisle Road. I thought I had a grab from a different angle, but this one from 'Duke of Duke' will do. It's where Bo and Luke first encounter Gaylord Duke in his XK-E. If you click here and you can see the hills in the background (although the foreground has changed a far bit). Here's the same intersection as seen from East Carlisle Road. This picture is from the start of Cletus's skateboard stunt from 'The Late J.D. Hogg' (see above for how it ended). I'm guessing they had to use two locations because there's no water here and no hill near the fire station. In this shot there's not a house in sight. If you clicked on the previous link you can spin around and see the entrance to Sycamore Canyon Drive and Denver Springs Drive on top of the hill, both of which have been built since Dukes was filmed. This is the view up East Carlisle Road from the car that Cletus nearly hits (the one in the previous picture). The house on the hill is still there, but the trees around it have grown and it now has neighbors.