See how Philadelphia compares to other notable cities in the chart below:
The news at the suburban county level for our area is not as rosy. Bike commuting levels remain stubbornly low, with all the PA counties each reporting just a 0.2% bicycle commute mode share. Our nearby New Jersey counties are more diverse. Gloucester County registered the lowest rate in the region, at 0.1% or one in a thousand, and zero female bike commuters. Only Mercer County, NJ reported a bicycle commute share that was above the national average of 0.64%.
The American Community Survey conducts its research via telephone surveys. They call residents and ask what his or her "primary mode of transportation" to work was the previous week. Biked to the bus? You're counted as a bus commuter. Biked two days a week and drove the other three? You're a vehicle commuter. If they happen to catch a county the week after terrible weather, bicycle rates can be under-reported. So this data is certainly not without its qualifications, but it's one of the best pictures we have at the moment of the state of bicycle commuting in the country.
Oh, and Portland? Their bicycle commuting rate fell fro 6.3% to 6.1%. Not that we're counting.