US presidential candidates Kamala Harris and Donald Trump are polling within the margin of error, yet despite the expectation of razor-thin margins, the potential impact of one group of US voters remains a mystery. An estimated 2.8 million Americans, excluding military members, are eligible to cast their votes from overseas, according to the US defence department. Depending on what states they hail from, these voters could impact the outcome of an election. Some organisations also estimate the number of US voters abroad to be even higher. In 2020, there were more than 224,000 ballots from citi…