The later Nishikis (generally, the ones with unicrown forks like the two most recent examples in this thread) were made by Derby in the Kent, Washington, plant, alongside Raleighs and Univegas. Derby retired the Nishiki and Univega lines to concentrate on Raleigh in 2001. I dated my Nishiki serial number using Sheldon Brown's page on dating Kent Raleighs.