FOR more than four decades the construction of a general location theory has been a stimulating challenge to spatial theorists. Despite the productive efforts of Weber, Englander, Predohl, Ohlin, Palander, Hoover, Losch, and others, the goals of spinning a theoretical web and specifying the design of a corresponding operational model are still remote.2 However, the comparatively recent pioneering contributions of Leontief in developing input-output techniques for general equilibrium analysis are of consequence here. They permit an attack upon a specific set of significant problems which logically fall within the jurisdiction of a general theory of location and space-economy. analysis of changing interregional economic bonds and flows can be approached from several directions. input-output method as elaborated here implicitly assumes, for the most part, unchanging spatial relations between any producer and his suppliers. Only a limited amount of industrial relocation can be tolerated with any change in the basic parameters of the economic system at any given point of time. An alternative approach has been sketched for example in an unpublished memorandum by Koopmans.3 Such an approach would treat the space factor explicitly. It would permit major variation in the spatial extent of production for each firm and in the pattern of production and resource utilization. It would be consistent with major relocation of industry and population. It would reveal how distance actively conditions interregional economic relations.4 An operational model following this alternative, more desirable, approach is yet to be developed. This paper is concerned with the much more limited assignment of regional and interregional analysis within the rigid spatial framework necessitated by the postulates of input-output analysis.5 'The analysis in this article has greatly benefited from discussions with Guy Freutel and with Wassily W. Leontief, James S. Duesenberry, Leon Moses, and other members of the Harvard Economic Research project. However, the shortcomings of the analysis and the views expressed herein are the author's only. model to be developed through spatial aggregation is basically different from one constructed by Professor Leontief through national disaggregation (in his forthcoming Studies in the Structure of the American Economy, Chapter 4). Nevertheless, the two models should not be viewed as alternatives. Rather they are complements. Leontief balanced regional model is particularly useful for determining regional implications of national projections; the pure interregional model, for determining national implications of regional projections. (For elaboration of this point, see W. Isard and G. Freutel, Regional and National Product Projections and Their Interrelations, sections 7 and 8, paper prepared for Conference on Research in Income and Wealth, National Bureau of Economic Research, May 195I,) Since one can proceed by degrees from one type of model to the other, it is likely that after considerable experimentation an hybrid model, involving elements of both, may prove to have the most general utility. author's experience in directing the preparation and collection of the data and in carrying through the computations for the Leontief model has been of great value in setting up a feasible design for his own model. 'For a presentation and evaluation of these efforts see W. Isard, The General Theory of Location and SpaceEconomy, Quarterly Journal of Economics, Vol. 63 (November I949), pp. 476-506. 3T. Koopmans, Optimum Geographical Distribution of Population and Industry in the United States (Cowles Commission for Research in Economics, January I946). 'Though trade theory is basically concerned with flows, it has by and large ignored or set aside the space factor. This is in line with the economic theorist's customary preoccupation with the time factor. ;;Treating space implicitly or as a passive factor has also been characteristic of the better regional development studies. Colin Clark in his excellent works on economic progress in the various regions and nations of the world (The Conditions of Economic Progress, London, I940, and Economics of I960, London, I942) does not attempt at all to study the basic changes in the spatial interrelations and patterns of these nations or regions. Nor does he probe into the diverse spatial structures of nations and regions at a given point of time. To be sure, he makes spatial comparisons in the sense that he compares nations having different latitudinal and longitudinal positions. But such comparisons more accurately fall under the heading of description, not spatial analysis. A. J. Brown (Industrialization and Trade, London, I943, and Applied Economics, London, I947), in ascribing a significant role to the world's uneven pattern of resources and its implications for specialization and the global locational structure of industry, takes a major step forw7ard. But he does not transcend geographic positional analysis. He does not expose the fundamental spatial scaffolding of international relations. Nor do E. F. Staley (Woorld Economic Development, Montreal, I944), the

N previous issues of this Review,1 one of the present authors presented material to demonstrate the occurrence of a seventeen-toeighteen year cycle in the development of the United States for the period I825-I933. This cycle was designated the transport-building cycle and was found to exist in such comprehensive and strategic series as transport development, immigration, urban population growth, bituminous and anthracite coal production, pig iron production, wholesale prices, and building, and in the general growth of Chicago. At approximately the same time as that material was presented, the outstanding work of Professor Edwin Frickey, Economic Fluctuations in the United States,2 appeared in which the conclusion was reached that within the geographic and temporal setting, of the study, there is analytical evidence of the presence of one, and only one, definite pattern of fluctuation. 3 And a few years later the monumental volume, Measuring Business Cycles, by Professor Wesley Mitchell and Professor Arthur Burns 4 was published in which the authors maintained that there was no compelling reason at the present time, nor even any real justification, for organizing cyclical measures of our time series on the assumption that business cycles undergo cyclical swings within periods of long building ' which periods correspond closely to the periods of transportbuilding cycles. In the light of such statements by these authorities, the existence and significance of transport-building cycles might be doubted, a priori. But upon further scrutiny, the statistical material embodied in Frickey's study is found to lend considerable support to, rather than discredit, the hypothesis of transportbuilding cycles in United States experience. And further it is found that Burns and Mitchell arrive at the cited conclusion by employing a test which is neither good nor relevant. First consider Frickey's data. For his series to show evidence of a transport-building cycle, averaging roughly seventeen-to-eighteen years in duration, it might be expected, following Schumpeter's and Hansen's classifications of cycles, that each transport-building cycle should include two Juglar 6 or major 7 cycles. Further, since it has been maintained that the correspondence is of such a form that the depression phase of every other Juglar or major cycle coincides with the depression phase of a transportbuilding cycle,8 it should be expected that in series in which Juglar or major cycles are superimposed upon transport-building cycles, every other Juglar or major cycle depression would be unusually severe and long. More specifically, since Frickey's study covers the period i866I9I4, and since troughs of transport-building cycles have been observed to have occurred roughly during the years, I860-64, I875-79, I894-Io90, and I9I4-i8, depressions of unusual length and severity should be expected in various time series some time during the years I875-7Q and I8Q4-I90oo.9

AN article in an earlier issue of this REVIEW 1 demonstrated the presence of the transport-building cycle in several important and comprehensive economic series for the United States. Mention was made of the relation of this cycle to another basic aspect of United States development, namely, urban growth. In the present note, specific consideration will be given to the existence of the transport-building cycle in the physical growth of the city of Chicago.2 Chart i is composed of a reference transportbuilding pattern for the United States,3 and of series depicting the five following types of activity representative of Chicago's physical growth: land subdividing, building, lumber receipts, manufacturing (number employed), and population growth.4 Land subdividing (representing area expansion of the city), building activity (representing structural growth), and annual population increase are three series basic to any study of urban physical development. Lumber trade throughout the nineteenth century was a dominant commercial enterprise at Chicago; and the number employed in manufacturing is a rough physical measure of the city's industrial growth.5 Examination of the movements of the five series discloses cycles that correspond to those designated as transport-building cycles in the series for the United States (top curve of Chart I). The troughs occur in I838-43, I858-62, I8748o, I896-I90I, I9I7-I9, and 1930-32. For each series and for the five series as a whole, measuring from trough to trough, the length of the cycles averages around eighteen years. With respect to timing, the series are highly synchronous; moreover, comparison of the trough periods for the Chicago series with those for the United States series reveals only minor differences. Save for population growth, which shows some tendency to lead during the nineteenth century, the Chicago series conform 1 Walter Isard, A Neglected Cycle: The TransportBuilding Cycle, this REVIEW, XXIV (I942), Pp. I49-58. 2Chicago was selected for study because (i) an abundance of data, dating from the city's infancy, was available, (2) Chicago is a primary center, (3) forces causing Chicago's growth were general and affected the development of most cities. 'This reference pattern was constructed on the basis of the series presented in the aforementioned article. The heavy solid lines represent the intervals containing the troughs of the individual series for the United States. (See Walter Isard, op. cit., p. I55, Table I.) Similarly, the horizontal dashed lines represent intervals within which the peaks of these series were reached (except that of wholesale prices during the Civil War). The peak and trough intervals are connected by dashed lines. For reasons presented in the earlier article, dating of cycles is from trough to trough, and only slight significance for purposes of timing should be attached to the peak lines of the reference pattern. Moreover, this pattern should not be construed as a composite picture of United States economic growth, nor as a cycle curve. Rather, it is a rough portrayal of transportbuilding movements isolated from other fluctuations, in which no attempt has been made to ascribe turning points and various phases to the cycle. 'Data on land subdividing, building, and population are available in H. Hoyt, One Hundred Years of Land Values in Chicago (Chicago, I933), pp. 474-83. Mr. Hoyt has described cycles in Chicago real estate which correspond closely to five of the transport-building movements. He does not include, as a cycle, movements between I899 and I9I7. Apropos of building activity, both value of buildings recorded in permits and number of building permits have been charted. The movements of these two series are in close harmony; and, for the earlier years when data on number of building permits are not available, value of new buildings, though not a measure of physical growth, may be taken as indicative of such. Lumber receipts for I833-42 are estimates from Industrial Chicago (Chicago, I89I-96), Vol. III, p. I93; data for I843-7I were taken from Chicago Herald, Illustrated History of Chicago (Chicago, I887), p. 83; from I872 on, Chicago Board of Trade, Annual Report. Data on number employed in manufacturing were pieced together from numerous sources: i850, i86o: United States Census Office, 7th Census, I850 and 8th Census, i86o; I854-56, I869-70: Chicago Herald, op. cit.; I857: Daily Democratic Press, Chicago, estimates for manufacturing activity approximately the same as for I856; i86i: Chicago Board of Trade, Annual Report, I86I; I872: E. Chamberlin, Chicago and its Suburbs (Chicago, I874), p. I29; I87398, Chicago Tribune, Annual Review Section. These data are not strictly comparable and must be interpreted with caution, especially with regard to short-run movements; in describing long-run cyclical movements, it does seem permissible to use them. Annual figures for number employed in manufacturing were not obtainable after I898. To bring into stronger relief the depression of this series in the midnineties, a dashed line has been projected for several years after I898, which roughly conforms to the manufacturing growth of Chicago during those years. 'It would have been desirable to use physical output rather than number employed, but output data were not available, and it was thought highly inadvisable to deflate value statistics by a price index constructed from very scanty material.

IN THE three and a half years since Hiroshima, considerable loose talk about atomic power has circulated among both scientists and laymen. At first people envisioned virtually costless power. Upon more sober reflection they realized that even if the cost per kilowatthour of the atomic fuel were to approach zero other important items in the cost of generating power would be far from zero.' But though this realization has become general, what discussion there has been of the cost of atomic power has proceeded on an elementary and unrefined basis. As yet the estimates which have been made of the costs of generating electricity in atomic stations are highly tentative. All existing nuclear piles have been constructed for non-power purposes, and there is great uncertainty about both capital and operating costs of the pile, chemical and metallurgical plants, and heat exchanger of the future atomic plant. Little if any significance, therefore, should be attached to the numerical estimates of costs of atomic power used in this paper. Our purpose is to discuss the implications of what can now be perceived about the probable characteristics of the costs of atomic power plants and to bring out certain economic relations which will be of importance when, through accumulated experience, nuclear engineers are in a position to make fairly exact cost estimates.