SEPTA is cosponsoring a “hackathon” this weekend to produce apps that use its wealth of data for riders.

Public agencies have always collected and used vast amounts of data, while offering only a small fraction of it back to the public – often in less-than-user-friendly ways. But in the last several years – spurred by the spread of smartphones such as Apple’s iPhone – something unexpected has been born: a largely organic public-private partnership, in which agencies make data more easily available, and app developers use the data to try to make money by making people’s lives easier and more efficient.