A disability or illness could occur in a closer proximity to an election and inhibit a person’s ability to vote if, in order to make other arrangements (i.e. absentee voting, voting by mail, etc), it required them to make plans ahead of time. Suppression isn’t always a deliberate action but sometimes an inherent aspect of a system.
“A Government Accountability Office (GAO) report found as recently as 2008, only 27 percent of polling places were barrier-free. In fact, the Federal Election Commission confirmed that, in violation of state and federal laws, more than 20,000 polling places across the nation are inaccessible, depriving Americans with disabilities of their fundamental right to vote.”
As per overseas personnel:
“In the 2012 presidential election, some 250,000 overseas and military voters who apparently wanted to vote were unable to navigate the system. While overall the military population will vote at a higher rate than the general population, those stationed overseas vote at a significantly lower rate. The voting rate among overseas military personnel for that election was probably less than 20 percent, a sure sign that there’s more work needed to ensure the full enfranchisement of Americans serving their country abroad.”