SACRAMENTO, Calif. -- Donald Trump’s election as president is giving a big social-media boost to an unlikely effort in the nation’s most populous state: a plan to vote on seceding from the union. The Yes California Independence Campaign hopes to put a question on the November 2018 ballot that would authorize a statewide independence vote for the spring of 2019. The effort drew little attention until Tuesday’s election, which also kept Trump’s fellow Republicans in charge of Congress and raised the possibility of a conservative shift on the U.S. Supreme Court. Any effort to get an issue on the ballot...