the town is sometimes said to have been named for the cimarron river, but both forks there are far upstream and both are reddish. the river through tulsa is a not a fork but a merger of the cimmaron, but it is the reddish fork of the arkansas from where it joins the normally blue-green verdigris river downstream. the contrast in color was striking to early explorers coming upstream, and resulted in the naming of the river.