The government of Vietnam has announced a change to their visa policy Tourist and Business visas for U.S. citizen's effective September 6th 2016 visas for U.S. citizens will now be valid for 1 year and good for Multiple Entries, Valid for Stay up to 180 days.

The length of stay will be determined by the immigration officials at the point of entry into Vietnam.
This change eliminates the 1 and 3 month single entry visas, 6 month multiple entry and the need for prior government issued approval to be issued a 1 Year multiple entry.