National (USA)

League of American Bicyclist (LAB) National organization advocating bicyclists rights, promoting cyclists education and sponsoring regional rallies of bike enthusiasts.  Head office is Washington, DC.
National Greenways Movement
Thunderbird Alliance A national coalition of organizations advocating for bicyclists.

Alberta, British Columbia

Edmonton Bicycle Commuters  Making bicycling an attractive alternative to commuting by car in Edmonton, Alberta, Canada
Better Environmentally Sound Transportation (BEST) One-less-car advocacy group in Vancouver, British Columbia, Canada.
Bikeways Advocating bikeways in British Columbia, Canada.
British Columbia Cycling Coalition (BCCC) Represent the interests of cyclists provincially and seeks to secure their recognition in policy and programs affecting transportation cycling.
Pedal Power [Pedal Energy Development Alternatives] develops and promotes the use of pedal powered technology, Vancouver, British Columbia, Canada.
Vancouver Area Bicycle Coalition (VABC) Advocacy organization for the lower mainland of British Columbia, Canada.
Greater Victoria Cycling Coalition The bicycle advocacy organization for Vancouver Island, British Columbia, Canada.

California

Bicycle Civil Liberties Union (BCLU) Based in Berkeley, California.
California Bicycle Coalition Creating a new cycling culture in California
Los Angeles Bicycle Coalition Working to improve the bicycling environment and quality of life in L.A. County.
San Francisco Bicycle Coalition (SFBC)  Advocacy organization working to transform San Francisco California's streets and neighborhoods into safer and more livable community.
Santa Barbara Bicycle Coalition Promoting bicycling for safe transportation and recreation in Santa Barbara County, California.
Silicon Valley Bicycle Coalition (SVBC) A forum for bicyclists to organize, discuss common concerns, and take action. Covers Belmont, Campbell, Cupertino, Gilroy, Los Altos, Los Gatos, Menlo Park, Milpitas, Morgan Hill, Mountain View, Palo Alto, San Jose, San Mateo Co., Santa Clara, Saratoga, Stanford, Sunnyvale, and Woodside.
Western Wheelers Bicycle Club Getting people in the saddle from Palo Alto, California USA

Washington Area Bicycle Association Promotes bicycling in the District of Columbia, Virginia and Maryland.
Gainesville Bicycle Club Helping to get gators on their bikes.
Georgia Bicycle Federation Dedicated to Making Georgia the most bicycle-friendly state in the nation.
Hawaii Bicycling League Perpetuating safe bicycling as a recreational activity, competitive sport, and as a means of transportation.
Bicyclists of Iowa City Bicycle advocacy, advancement, and fun in the Iowa City, Coralville, Hills, North Liberty, Lone Tree, Riverside, & the surrounding Johnson County, Iowa.

Massachusetts Bicycle Coalition (MassBike) Improve bicycling conditions for all types of cyclists.
Bicycle Coalition of Maine Working for better biking in Maine.
Minnesota Bicycle & Pedestrian Alliance Advocating non-motorized land travel in the land of 10,000 lakes.
Trenton Cycling Revolution Creating a safe and healthy environment for bicyclists in Greater Trenton, New Jersey, through education, advocacy and promotion.
Massapequa Park Bicycle Club Friends riding together, lots of eating and hanging out in Massapequa, New York.
Transportation Alternatives (TA) 4,500-member advocacy group for safer cycling and walking in New York City.
Velo New Brunswick Bicycle news from eastern Canada

Ontario, Oregon, Texas, Wisconsin, Washington

Ottawa Bicycle Club Canada's oldest and largest bike club.
Transportation for Livable Promoting alternative transportation in Hamilton ON
Bicycle Transportation Alliance (BTA) Advocacy organization, Portland, Oregon. Get the low-down on activism in Oregon.
Bicycling In Austin Primarily covers Austin, Texas, but contains a wealth of general information.
Greater Dallas Bicyclists (that would be Texas)
Texas Bicycle Coalition Advancing bicycle access, safety and education.
Bicycling Community Page Bicycling from Madison and Dane County, Wisconsin (may be defunct)
Bicycle Alliance of Washington (BAW) Champion non-motorized transportation in Washington State. 
Cascade Bicycle Club (CBC) Long regarded as one of the best bike clubs in North America, it is continually innovating, Seattle, Washington.

To IBF's America's index