Distance, operation overlap, sensory cues, and frequency of positive interactions have an influence on the probability individuals will maintain social ties and collaborate together. People tend to collaborate with stronger ties in their networks. This is why cities matter for economic development. While individuals and organizations can work together over a large distance, the closer they are the greater the chance they will collaborate with one another and maintain ties. Research on the effects of distance on collaboration has concluded collaboration drops off significantly between one-quarter to a mile. Companies in the same industry located less than a mile of each other experience ten times greater information flow than those located two to five miles apart. After five miles, knowledge flow drops off continually at a lesser rate. Interestingly specific industries become more concentrated than others.