A tractor on top cotton harvester for supporting a tractor on a platform directly over a cotton harvester picker unit or units, providing steerable front wheels and a direct sightline through the platform for viewing the steerable wheel position and entry of cotton plants into the picker unit or units to avoid running over plants and possible boll damage or loss. The harvester carries a cotton receiving basket at a rear of the platform, and a tractor driven blower and ducts for directing a flow of airborne picked cotton from each picker unit into the basket.