The Southeastern Pennsylvania Transportation Authority (SEPTA) oversees Philadelphia's subway, trolley, and bus systems. SEPTA also operates bus routes and regional rail lines in Bucks, Chester, Delaware, and Montgomery Counties. SEPTA offers a price per ride, a price per day, a price per week, and a price per month; it's up to you to figure out which is the most cost-effective at any given time. On the plus side, two children (under 42 inches) may ride free at all times while accompanied by fare-paying adult. Additional children accompanying the same fare-paying passenger are carried at the base fare, plus applicable transfer and zone fees required on non-holiday weekdays. On weekends and major holidays, up to two children (11 years old and younger), accompanied by a fare-paying adult, may travel for $1 each, plus applicable transfer fees. Additional children accompanying the same paying passenger are carried at the adult base fare, plus applicable transfer and zone charges. SEPTA does not give change, so if you enter a bus without a token, have $2 ready to hand over. You can extend your ride by transferring from one transit vehicle to another. A transfer ticket for $.75 can only be purchased at the time of boarding to continue a one-way journey involving one interchange on certain intersecting routes within the city fare zone or a suburban fare zone. The transfer provides a 70% discount off the cash fare. A re-transfer ticket can also be purchased at a 70% discount in order to complete a single continuous one-way trip involving a second paid interchange between certain intersecting routes with the City Fare Zone, or a Suburban Fare Zone. A single one-way trip is limited to two transfers. It is also valid for a one-way ride on any Commuter or Airport Railroad Train. The Convenience Pass ($6) is valid for a single day's travel of up to 8 one-way trips in either direction on bus, subways, and trolleys, and is valid until 2am the following day. It may not be used for travel on regional rail. The Weekly TransPass ($20.75) provides unlimited travel for all Zone 1 rides on any transit route and is valid for one fare zone in Philadelphia or Suburban routes, and may be used during off-peak hours within the geographic boundaries of Philadelphia on Regional Rail. The weekly TransPass also provides unrestricted travel "anywhere" on the entire SEPTA system on weekends and holidays. The Transpass is valid for unlimited trips from 12:01am Monday of the week for which it is valid, through 2am the following Monday. A Weekly and Monthly Trailpass is valid for travel on regional rail lines to destinations in the rail zones listed on the passes. They are also valid for travel on bus, trolley, and subway/elevated routes. Discounts for groups, senior citizens, children, students, and families are also available.