Hubert Blalock predicted that the occurrence of lynching in southern communities should be positively related, with increasing slope, to the proportion black of the population, but methodological problems of computing a rate have precluded testing the prediction. A model of random interracial interaction suggests computing the rate with a term containing the proportion black and the proportion white, and—using this rate—Blalock's prediction is upheld for Mississippi counties in the period 1889–1930. The height and shape of the curve relating this rate to percent black varies from state to state, and it is suggested that such variation could be profitably related to variation in historical and governmental properties of the states.