This Copper Ore farming guide will show you the routes that I use for farming Copper Ore in Classic WoW.
Copper Ore
If you want to farm different ores, please see my other guides:
Tin Ore 
Iron Ore 
Mithril Ore 
Thorium Ore
Durotar
After you clear the cave marked with the red circle, go left, then jump down.
Dun Morogh
The respawn rate is fast enough that you don't have to loop around the whole zone, so you can use these two routes. If you have competition, you should move between the two routes while mining copper between them.
Elwynn Forest
Low level characters should skip both caves.
Tirisfal Glades
Mulgore
High level players should always enter the Venture Co. Mine because you will get around 8 Copper Veins from clearing both the mine and the small area after the mine at the side the mountain. (you can only access this area from the mine)
It can be a nightmare to find the exit the first time you are there so I included a small map. You won't see this map in-game, because it's from the Cataclysm expansion, but the layout is the same. Make sure to go to every corner of the cave!
Low level characters should skip both caves.
Darkshore
