five inhabitants (Slaughter Beach, Delaware) up to Seattle, Washington, with nearly half a million inhabitants. The 'nearest neighbour was defined for each of the sample towns using Thomas's probability definition, equation (4.15), and first, a correlation analysis of spacing as a function only of size was carried out. Table 4.8 shows that the association discovered, though statistically significant, explained only about 2 per cent of the variations in spacing. Divisions of the sample into central places (162 towns) and non-central places showed that the spacing of the first group was marginally more predictable than that of the second. A breakdown of the tons into five major farming zones brought out important variations between the regions of the United States. In the Great Plains and the Far West the level of explanation rose sharply to over 40 per cent and in the Corn Belt to over 20 per oent,suggesting that the regularities described by LOsch (1954, pp. 389-93) might be less typical of the whole United States than often supposed.