This paper describes a methodological study attempting to improve the quantitative analysis of migration data by controlling for seven important spatial variables. A primitive mathematical model is constructed by means of which theoretical migration frequencies are calculated and then compared with actual frequencies, yielding several indexes and a Force of Attraction. This approach was applied to United States internal migration for 1935–1940. The highest scores were obtained for the Pacific area. This model may be used for human, animal, or inanimate movements.