Route 3 is the third route in the Kanto region. It connects Pewter City to Mt. Moon, and is the first route to actually have trainers. It is in a zigzag shape, and there are many ledges to hop over. Open grass areas are located at the near-end of the route, towards the entrance of Route 4.
Route 3 is surrounded by mountains on all sides. Upon entering the route, the road forks and the player character can choose to take the northern route, which leads to Mt. Moon or the southern route, which leads to an area filled with craters. Several trainers are found on this route and the player character must make his way through by battling them.
There are several parallel ledges near the entrance of the route in the west and the Pokémon Center in the east. Large patches of grass and multiple trees can be found after the player character travels through the first series of ledges, and in the area south of the Pokémon Center, which is partially fenced around a corner and a signpost with directions can be found. Several boulders and rocks are found near the Pokémon Center, and the latter can be smashed with the use of Rock Smash to obtain items. To the north of the Pokémon Center lies the entrance to Mt. Moon.
Route 3 made an appearance in Gyarados Splashes In!, where Red encountered Misty trying to tame a rampaging Gyarados. After Red helped Misty by using Saur to stop and catch Gyarados, she told Red that it was hers and that it had gone missing earlier and started rampaging when it returned.
Route 3 made an appearance in Clefairy and the Moon Stone when Ash and co. traveled through it to reach Mt. Moon. There, they encountered a man who was being attacked by a flock of Zubat and after Ash ordered Pikachu to use Thunder Shock to disperse the flock of Zubat, he thanked them and introduced himself as Seymour.
Route 3 made a minor appearance in File 1 - Red, where Red was seen travelling through it after obtaining the Boulder Badge from Brock.