If you were to just judge it by the name, one would assume Amazon Prime Day 2020 would last for just 24 hours, a full day, but that's not the case. The first few years, Amazon stared the event in the morning, and ended it at night, but three years ago the event spread to a 30 hour span, and then two year it was 36 hours. In 2019, the Prime Day event spanned a full 48 hour period, and it's likely that we will see the same happen in 2020.
Back in 2017, Amazon reserved the first few hours of the event to offer exclusive deals for Voice Shoppers only. This meant you had to have an Echo device in order to order the items via an Alexa voice command, but last year there was no exclusive period for that. As the event gets bigger, Amazon stretches it to last longer and longer. Last year the company boasted millions of deals throughout the span of Prime Day, and there's no way we could see them taming that down any.
We will be updating this as soon as we hear more official information from Amazon, so be sure to stay tuned.