• 26 February 2007: Arizona, California, New Mexico, Oregon, and Washington form the Western Regional Climate Action Initiative. • 24 April 2007:
British Columbia joined with the five western states, turning the WCI into an international partnership. • 21 May 2007: Utah became the sixth state to join the WCI when Governor
Jon Huntsman Jr. signed the Initiative. Huntsman was the second Republican governor to join, after California governor
Arnold Schwarzenegger. • 13 June 2007: Manitoba said that it would be the second Canadian province to join the WCI. • 24 September 2007: Alaska joined the WCI as an observer. • 19 November 2007: The Governor of Montana announced that his state would also join. • January 2008: Montana officially joins the WCI. • 18 July 2008: Ontario, previously an observer, became a partner. • 29 June 2011: California announces that enforcement of the cap will be delayed one year to allow the necessary elements of the program to be in place and fully functional. The stringency of the cap and expected amount of emission reductions, however, will remain unchanged. • 6 July 2011: In order to maintain a coordinated approach to implementing the regional program, Quebec announces a one-year delay in enforcement of the cap. • 18 November 2011: Arizona, Montana, New Mexico, Oregon, Utah and Washington leave WCI formally. Participation by BC was cast into doubt also, where officials indicated satisfaction with the existing
carbon tax approach and had not committed to implementing a
cap and trade system to replace it. As of December 2011, the remaining WCI partners were California and the Canadian provinces British Columbia, Manitoba, Ontario, and Quebec. • 11 May 2018: Nova Scotia becomes WCI partner, and executes cap and trade program on 1 January 2019. • 11 October 2018: Ontario passes the Cap and Trade Cancellation Act, 2018 and formally withdraws from the WCI. After
British Columbia ceased participation in
emissions trading in 2018, it remained a participating jurisdiction under WCI by-laws until amendments were made. Nova Scotia withdrew itself as a participating jurisdiction in 2024. , the participating WCI jurisdictions are the American states of California and Washington; and the Canadian province of Quebec. ==See also==