His book Walking the Beach to Bellingham is an autobiography and manifesto fleshing out his journal of a hike along the shore of Puget Sound over a two-year span.

[2] Manning is most famous for being the editorial committee chair for the first edition of Mountaineering: The Freedom of the Hills, a textbook for climbing and scrambling.

Manning believed foot traffic (both the boots and the horseshoe variety) cannot coexist with the greater speeds of bicycle enthusiasts and disdained local politicians beholden to wheeled-recreation advocates for "spouting pure Lycra".

His final book, published by NCCC, is "Wilderness Alps: Conservation and Conflict in the North Cascades," and details the history of the preservation movement there.

With the goal of preserving wildlands within urban King County, Manning designated (in the pages of Footsore 1) the odd twenty mile-long (32.2 km) spur of Cascade Mountain foothills along Interstate 90 near Seattle as the "Issaquah Alps" and founded the Issaquah Alps Trails Club in 1979.