Oil Drillers’ Rocky Mountain High Threatened by Colorado Vote

BP Plc’s new U.S. onshore oil headquarters in Denver is filled with images of Colorado’s regal mountains, its expansive forests, its nature-loving culture.

Aspen trees line the BP club room, newly installed beer taps await local craft brews, multiple stone fireplaces invite cozy discussions about ski conditions, and a 52-foot pine tree, sliced in half, serves as a conference table.

Whether Coloradans want the tribute is another matter.

On Nov. 6, voters may spoil BP’s welcome. That’s when Colorado decides whether to limit drilling in an initiative that some say could cut the state’s oil output by more than ...