The locations and profiles of firms in the six-county Chicago, Illinois, region were used to compare the businesses' proximities to freeway ramps and transit stations for two time periods: 1981 and 1999. A series of regression models was constructed to assess whether the location patterns with respect to transportation facilities have changed over the last two decades. The data suggest that, controlling for exogenous factors, businesses have moved closer to freeway ramps in the last two decades. Meanwhile, the distance to transit stations has not changed except in the city of Chicago, where it has decreased. These findings suggest shifts in location choice behaviors in the urban core and the suburbs. Specifically, firms in the urban core areas are valuing access to rail stations to a greater degree, whereas those in the suburbs are placing more importance on proximity to freeway ramps. The concentration of businesses near expressway ramps in the inner and middle suburbs suggests the emergence of a pattern in those areas that corresponds to a polycentric development, with freeway ramps as the focal points. Finally, the findings indicate a shift, not a decrease, in the importance of transportation access for business location choice.