As I mentioned earlier, the opening scene takes place in 1986 and features a television commercial for Hands Across America. It was a real charity event held in order to raise awareness about famine in Africa and homelessness in the US, involving 6.5 million people linking hands on Sunday, May 25, 1986 to form a human chain. The benefit ended up raising $34 million, but less than half of that money went to the cause due to large promotional costs.
So, why does Peele include Hands Across America so heavily in his film? The event is essentially acts as an allegoric backbone for the presence of the evil doubles that takes up the back half of Us. Not only is the charity event likely one of the last things young Adelaide remembers before she's cruelly doomed to the world of the Tethereds underground, with Red assuming her spot up above, but it's also a metaphor for how often people in the upper and middle class turn a blind eye to the poor who struggle with the impossibility of rising above their station.