For the record, you always need a valid passport that is not expired in order to enter any country. However, if you have a valid visa on an expired passport, you can bring that passport along with your current valid passport to travel to the United States. And although some countries are adopting passport administration strategies to take your old passport away from you, there are still some scenarios where you could have a valid visa on an older passport. In these cases, you are allowed to use the visa on your old passport to enter the US.