In an unprecedented move, the US State Department issued a Level 4 travel advisory of "Do Not Travel" for the entire world on March 19, 2020. A Level 4 travel advisory means that the US State Department doesn't recommend visiting the country for any reason. It's usually reserved for the outbreak of war, terrorism, or humanitarian crises like famine. There were only 16 countries on a Level 4 advisory before the announcement was made, including Afghanistan, Syria, Libya, Iran, and China.
The State Department also issued a notification on Twitter on March 19, 2020 that passport application processing would be halted except in specific circumstances such as life-or-death emergencies or within 72 hours.
An alarming section of the advisory notifies Americans that they should return home as soon as possible or hunker down wherever they happen to be. There is a specific recommendation to make travel plans that don't require the assistance of the State Department. Some Americans are finding it difficult or impossible to get US Embassy assistance in escaping from countries with already closed borders.