Town twinning begins for a variety of reasons. Generally, partner towns have similar demographics and size. They may arise from business connections, travel, similar industries, diaspora communities, or shared history. For example, the partnership between Portland, Oregon and Bologna, Italy arose from shared industries in biotechnology and education, and a "similar attitude towards food", whereas Chicago's link with Warsaw, Poland began with Chicago's historic Polish community. The twinning of Indianapolis with Monza, Italy is due to both cities' long association with auto racing.