If the US national elections on November 5 go smoothly, not long thereafter we will know whether Democratic Vice President Kamala Harris or Republican former president Donald Trump will be the nation’s next leader. The result could make the difference between a relatively stable and prosperous future, not just for the United States, and a path to decline and insecurity at home and abroad. American expatriates in Hong Kong have the potential to influence who moves into the White House. They could also determine which party — centre-left Democrats or populist right-wing Republicans — will contro…