Retail sales in 1963 in 116 Standard Metropolitan Statistical Areas (SMSA’s) are related to SMSA size in 1960. Nucleated sales occur in the Central Business District (CBD) and in Major Retail Centers (MRC’s). As SMSA’s grow, the proportion of sales in MRC’s increases and that in the CBD decreases. The ratio of nucleated sales to dispersed sales remains constant. The laws of economic location operate to place shopping goods primarily in the CBD and in MRC’s whereas convenience and other types of stores disperse throughout the SMSA. Plotting the straight line distance of every MRC relative to the CBD and computing the mix of trade types in MRC’s reveals that, with some modifications, most MRC’s have a mix of store types similar to the CBD. Convenience stores are somewhat more important and all other stores less so than they are in the CBD. The findings support the Harris-Ullman multiple nuclei hypothesis.