1940

P. C. Mahalanobis,  "A sample survey of the acreage under jute in Bengal", Sankhyu 4, 511-530.
The well-known statistician Mahalanobis discusses some aspects of TSP solutions through randomly chosen locations in the Euclidean plane.   This work was in connection with a survey of farm lands in Bengal that took place in 1938, where one of the major costs in carrying out the survey was the transportation of men and equipment from one survey point to the next.   This work appears to independent of the Merill Flood led efforts on TSP applications that took place several years earlier.

1942

R. J. Jessen,  "Statistical investigation of a sample survey for obtaining farm facts",  Research Bulletin #304, Iowa State College of Agriculture.
The title suggests that this report deals with a problem similar to the application studied by Mahalanobis.   If this is the case, there may be a case for referring to the TSP as the "traveling farmer's problem."   We were not able to obtain a copy of this paper.   We would certainly appreciate receiving any information on how we could locate this historically interesting paper.

1949

J.B. Robinson, "On the Hamiltonian game (a traveling-salesman problem)", RAND Research Memorandum RM-303.
This paper is the earliest reference we could find that uses the term "traveling salesman problem" in the context of mathematical optimization. The introduction to the paper, however, makes it clear that the TSP was already a well-known problem at that time (at least at the RAND Corporation). The paper contains an algorithm for solving a variation of the assignment problem (given a complete directed graph, with weights on the arcs, find a minimum-weight set of disjoint directed circuits that cover the nodes of the graph) is described. The author writes that she was led to the solution of the problem in an unsuccessful attempt to solve the TSP. In the introduction to the paper, the TSP is described as follows: "One formulation is to find the shortest route for a salesman starting from Washington, visiting all the state capitals and then returning to Washington." It is interesting to note that this is the instance that was solved several years later by Dantzig, Fulkerson, and Johnson.