Originally Posted by jeneralist

Yup, 4%. (For comparison, the Great Allegheny Passage has a 2% max.)
You can find another nice write-up about the railtrail at the NY Times website: http://travel.nytimes.com/2007/07/13/travel/escapes/13Ptit.html?pagewanted=all

The NY Times author clearly did her ride at a different time of the week, and a different time of the year; she emphasizes how busy the trail was, and for me it was almost deserted.