Riders can now tell the Southeastern Pennsylvania Transportation Authority (SEPTA) why they ride with Instagram.

Using the Instagram photo application, riders are encouraged to take photos of SEPTA during their daily use of the system and caption the photo with what riding SEPTA means to them, along with the hash tag #iseptaphilly. Photos are aggregated into a photo stream, which is live on the www.iSEPTAPhilly.com home page.

Weekly prizes, including tickets to concerts, 76ers games and Blue Mountain Ski Area and SEPTA passes and gear, will be awarded for the best pictures.

"We're looking for more than the 'I'm sitting on the train, heading to work' photos," said Elizabeth Bradford, director of marketing, SEPTA. "Our customers are creative. We're looking for them to use their artistic skills and submit inspired images of why and how they ‘SEPTA’ Philly. Let's prove the old adage true: a picture really is worth a thousand words."

The agency launched its I SEPTA Philly campaign in spring 2012 to attract the next generation of public transit riders:  people between the ages of 18 and 34. In unscripted commercials, riders talk about safety, cleanliness, ease of use and affordability — topics raised during focus groups held with individuals in the targeted age group. Throughout the summer, SEPTA asked riders to submit their I SEPTA Philly videos to the website.

"The video contest was a success," said Bradford. "The Instagram feed makes it even easier for our customers to tell us why they SEPTA Philly. They can upload their photos while they are still on the bus, trolley or train."

The photo contest is open to all members of the public and ends at noon on Dec. 21. Submitted photos will be reviewed by SEPTA staff for approval before being accepted for the contest and the website.