would swing back toward the medieval model, where students could enjoy significant autonomy in their choice of residence and habits. The trend of American students living off campus had emerged during the post-World War II era. The Servicemen's Readjustment Act legislation, popularly known as the "G.I. Bill", provided large numbers of returning veterans with the financial aid to pursue college degrees. Many veterans were older than traditional students or had families to support; this further spurred the growth of off-campus housing. It was estimated that by century's end, as many as 85% of American college students lived off campus (Carnegie Commission). This residential trend – and other factors – would mitigate the division between town and gown (but not necessarily the tensions). Universities increasingly integrated into cities as cities absorbed and accommodated universities. Commuter colleges, such as San Francisco State University, now enroll large numbers of students who live at a distance, commute to campus for classes, and then leave at the end of each school day. Concurrently, American universities have opened branch campuses and even offer classes in storefront venues. However, the recent integration of campus and community has not been without problems. For one thing, an urban university can generate major traffic and exacerbate parking problems in adjacent neighbourhoods. The quality of neighbourhoods near a university may deteriorate. Certain industries requiring highly educated workers, such as biotechnology, may be drawn to college communities. The growth of these knowledge economies, and additional upwardly mobile residents, may increase the competition for community space or drive up land costs. The expansion of campuses has led to the razing of some neighbourhoods and the displacement of large numbers of city residents. These factors create continuing tensions between town and gown, but in some scenarios, the university and the local community work together in revitalisation projects. Local residents and members of the university community may clash over other political, economic, and demographic issues. Some localities in the Northeastern United States have tried to block students from registering to vote in elections as local residents, instead demanding that they vote by absentee ballot at their parents' residence. Many universities in college towns are located on unincorporated land, which prevents students living in on-campus housing from voting in town elections. As urban universities increase in size and complexity, they hire a large staff of city residents. Labor unions have formed on campuses and bargain collectively