Today on his blog Paul Krugman put up his own description of the work for which he received the Nobel Prize in economics. I sent him a comment some hours ago asking what he had to say about some of the literature that preceded his 1991 paper on economic geography that mathemetically shows how agglomeration and spatial differentiation proceed, given that he did not, and never has, cited or mentioned any of this. Again, in his paper and elsewhere he has claimed to have provided the first such mathematical model. He has not posted my comment, although perhaps he will after several more hours.
Just for the record, here are two, although they are not the only ones, papers that appeared prior to his that use highly rigorous mathematical models to study agglomeration in spatial location models. I note that one of these was in a prominent economics journal.
Y.Y. Papageorgiou and T.R. Smith, 1983. "Agglomeration as Local Instability of Spatially Uniform Steady-States." Econometrica, vol. 51, pp. 1109-1119.
Wolfgang Weidlich and Gunter Haag. 1987. "A Dynamic Phase Transition Model for Spatial Agglomeration Processes." Journal of Regional Science, vol. 27, pp. 529-569.
This last paper contains a figure that closely resembles one that Krugman publicly presented during a session on complexity at the ASSA/AEA in the early 1990s, not offering any source for it other than himself, although, of course, it remains possible that he never read the paper.
Nevertheless, I continue accept that he is deserving of receiving the prize and even all by himself. Even if there are some question marks about literature citation or complete accuracy of some of his statements, his models have been very well done, and he has done very innovative work in other areas as well, such as foreign exchange rate modeling.