“…These well-documented features of U.S. cities, including Chicago (e.g., Johnston, Poulson, and Forrest, 2003;Massey, 1990;Wilson, 1987), are likely to restrain the mobility of its population, including offenders, and can be considered as a "social barrier" (Rengert, 2004). Pettiway (1982Pettiway ( , 1985 studied the mobility of burglars and robbers in Milwaukee and distinguished three types of areas on the basis of the racial composition of the population: the black ghetto area, the white non-ghetto area, and an interstitial area around the ghetto (where the composition was more racially mixed). He observed that those who lived in the black ghetto would overwhelmingly offend there, whereas those who did not offended outside the ghetto.…”