DANTZIG42 is the reduced problem obtained by Dantzig, Fulkerson, and Johnson in their classic 1954 paper on the solution of a TSP consisting of one city in each of the 48 continental states in the U.S., plus Washington, D. C. The authors worked with a 42-city instance, noting that the optimal tour through the 42 cities uses roads that pass through the 7 cities that were excluded. The instance is specified by the inter-city travel distances bewteen the 42 points; the authors write that the distance table was prepared by Bernice Brown of the Rand Corporation. The data set is part of the TSPLIB.