Omitting 1137 loci that are included in the location database but have only cytogenetic assignment, there are 605 loci in the integrated map that synthesizes physical and genetic data and subsumes a composite physical location, cytogenetic and regional assignments, mouse homology, rank, and references. With error filtration and allowance for interference the genetic length is 211 cM, to which the p arm contributes 100 cM. The physical length is 164 Mb, with 62 Mb in the p arm. Current problems in map integration are discussed and some solutions proposed.