In human geography, the new approach became known as “locational” or “spatial analysis” or, to some, “spatial science.” It focused on spatial organization, and its key concepts were embedded into the functional region—the tributary area of a major node, whether a port, a market town, or a city shopping centre. Movements of people, messages, goods, and so on, were organized through such nodal centres. These were structured hierarchically, producing systems of places—cities, towns, villages, etc.—whose spatial arrangement followed fundamental principles. One of the most influential models for these principles was developed by German geographer Walter Christaller in the early 1930s, though it attracted little attention for two decades.

Christaller’s central-place theory modeled settlement patterns in rural areas—the number and size of different places, their spacing, and the services they provided—according to principles of least-cost location. The assumption was that individuals want to minimize the time and cost involved in journeys to shops and offices, and thus the needed facilities should be both as close to their homes as possible and clustered together so that they can make as many purchases as possible in the same place. Likewise, businesses will want to maximize turnover, with people spending as much as possible on goods and services and as little as possible on transport. An efficient distribution of service centres was in the interest of both suppliers and consumers. Christaller showed that this required a hexagonal distribution of centres across a uniform plane (i.e., one that had no topographical barriers), with the smaller centres (providing fewer services) nested within the market areas of the larger.

Other works by non-geographers provided similar stimuli. Economists such as Edgar Hoover, August Lösch (who produced a theory similar to Christaller’s), Tord Palander, and Alfred Weber suggested that manufacturing industries be located to minimize both input costs (including the costs of transporting raw materials to a plant) and distribution costs (getting the final goods to market). Least-cost location was the goal, which could be modeled as a form of spatial economics. Efficient spatial organization involved minimizing movement costs, which was represented by an adaptation of the physicists’ classical gravity model. The amount of movement between two places should be a function of their size and the distance between them; i.e., size generates interaction, whereas distance attenuates it.

These hypothesized patterns stimulated much searching for order in the distribution of economic activities and movements between places. Use of the intervening areas between the nodes and channels was also investigated within the same paradigm. A 19th-century German landowner-economist, Johann Heinrich von Thünen, had modeled the location of agricultural production, involving a zonal patterning of activities consistent with minimizing the costs of transporting outputs to markets with the highest-intensity activities closest to the nodes and channels. Economists adapted this to the organization of land uses within cities: these, and the associated land values, should be zonally organized, with housing density decreasing away from the centre and the major routes radiating from it.

Finally, there was the issue of change within such spatial systems, on which the work of Swedish geographer Torsten Hägerstrand was seminal. He added spatial components to sociological and economic models of the diffusion of information. According to Hägerstrand, the main centres of innovation tend to be the largest cities, from which new ideas and practices spread down the urban hierarchies and across the intervening nonurban spaces according to the least-cost principles of distance-decay models. Later studies validated his model, with the best examples provided by the spread of infectious and contagious diseases.

The models of patterns and flows were synthesized to describe urban systems at two main scales: systems of cities, in which places were depicted as nodes in the organizational template, and cities as systems, focusing on their internal organization. The goal was not just to describe those systems and their operations but also to model them (statistically and mathematically), thus producing general knowledge about the spatial organization of society rather than just specific knowledge about individual places. Location-allocation models suggested both optimum locations for facilities and efficient flows between them. A new discipline, regional science, was launched by economist Walter Isard to study such systems and promote the application of the knowledge acquired. It failed to gain separate status within universities, but many geographers still participate in its conferences and publish in its journals.

By the late 1960s these new practices were synthesized in influential innovative textbooks on both sides of the North Atlantic. Notable examples included Peter Haggett’s Locational Analysis in Human Geography (1965), Richard Chorley and Haggett’s Models in Geography (1967), Ron Abler, John Adams, and Peter Gould’s Spatial Organization (1971), and Richard L. Morrill’s The Spatial Organization of Society (1970). Each emphasized the theme earlier pronounced by Wreford Watson that “geography is a discipline in distance.”

The early models made relatively simple assumptions regarding human behaviour; the principle of least effort predominated, with monetary considerations preeminent, and it was assumed that decisions were based on complete information. These were later relaxed, and more-realistic models of spatial behaviour were based on observed decision making in which the acquisition and use of information in spatial contexts took centre stage. Distance was one constraint on behaviour; it was not absolute, however, but manipulable, as patterns of accessibility could be changed. And as the behavioral contexts were altered, the learning and decision-making processes within them also changed, and the spatial organization of society was continually restructured.

As research practices changed, so too did teaching. The earlier focus on field observation, map interpretation, and regional definition was replaced, and research methods for collecting and analyzing data—particularly statistical analysis—became compulsory elements in degree programs. New subdisciplines—notably urban geography—came rapidly to the fore, as systematic specialisms displaced regional courses from the core of many curricula. Other parts of the discipline—economic, social, political, and historical—were influenced by the theoretical and quantitative revolutions. What became known as a “new” human geography was created, initially at a few institutions in the United States and the United Kingdom but rapidly spread through the other Anglophone countries and later to a variety of other countries.

Methods and machines

Mapmaking and remote sensing

The map was long the geographer’s main tool, with map construction and interpretation being the major practical skills taught in degree programs. Mapmaking involved knowledge of surveying and projections, in addition to the arts of depicting point, line, and area data on maps. Map interpretation involved their use not only in the field for location but also in the laboratory for identifying landscape and other features, with map comparison used to identify associations among distributions and to define regions with multiple criteria. Alongside the map—especially after World War II—geographers increasingly used aerial photography to supplement these landscape-interpretation skills.

By the end of the 20th century, very little of this material remained in degree curricula; mapping skills were seldom a significant part of the geography student’s education. Mapmaking was moved from the field and drawing board to the laboratory and keyboard, using remotely sensed imagery, geographical positioning systems (e.g., the Global Positioning System [GPS]), and computers. So was the production of maps to display patterns of interest to geographers; standard computer software packages provided geographers with their illustrative material without any need to use pen and ink.

The analysis of remotely sensed images—initially from airplanes but increasingly from spacecraft—assumed considerable importance in some areas of geographical research, especially physical geography. Images provided immediate, regular, and frequent information on parts of the world that were difficult to access physically, making it possible not only to produce detailed maps but also to make estimations of environmental conditions (such as biomass volume, soil wetness, and river sediment loads) and to assess short-term changes. Such images are the only source of data at the global scale and are increasingly important for modeling environmental changes.

Much experimentation was required to realize the potential uses of the massive volume of data provided from spacecraft sensors, and remote-sensing techniques became important tools; radar, for example, circumvented the problem of generating images in cloudy areas. The techniques for producing these newer images were largely the province of physics, mathematics, and computer science. Geographers were concerned with their use in understanding and managing the environment, with field studies providing the ground data against which image assessments could be evaluated, and developing remote-sensing methods for various tasks, such as estimating precipitation in desert areas.