It’s Election Day today, as people across the United States cast their votes in local races and ballot initiatives. Among the key issues at stake are campaign finance measures in Maine and Seattle, Washington; an initiative to legalize marijuana for both medical and personal use in Ohio; and a proposal in San Francisco to limit short-term rentals, a possible blow to the home-sharing website Airbnb. On the eve of the vote Monday, housing activists occupied Airbnb’s San Francisco headquarters, saying the firm’s model fuels gentrification and homelessness.