I assume all will be peaceful, so this is just a notice

UNITED STATES EMBASSY BELMOPAN, BELIZE
Security Message: Planned Demonstrations Monday, September 19
September 16, 2016

U.S. Embassy Belize informs U.S. citizens that a demonstration is expected to take place at Independence Hill in Belmopan from at 9:00 am - 1:00 pm on Monday, September 19. The Belize National Teachers’ Unionwill demonstrate to demand a pay raise and action in areas of national interest.
Review your personal security plans; remain aware of your surroundings, including local events; and monitor local news stations for updates. Maintain a high level of vigilance and take appropriate steps to enhance your personal security and follow instructions of local authorities.
Even demonstrations intended to be peaceful can turn confrontational and escalate into violence. You should avoid areas of demonstrations, and exercise caution if in the vicinity of any large gatherings, protests, or demonstrations.
For any emergencies involving U.S. citizens, please contact the American Citizens Services (ACS) Unit in the U.S. Embassy at ACSBelize@state.gov or by calling 501-822-4011.
For further information:
• See the State Department's travel website for the Worldwide Caution, Travel Warnings, Travel Alerts, and Belize Country Specific Information.
• Enroll in the Smart Traveler Enrollment Program (STEP)to receive security messages and make it easier to locate you in an emergency.
• Contact the U.S. Embassy in Belize, located at 4 Flora Park Road, Belmopan at +501-822-4011, 8:00 a.m. to 5:00 p.m. Monday through Friday. After-hours emergency number for U.S. citizens is +501-610-5030.
• Call 1-888-407-4747 toll-free in the United States and Canada or 1-202-501-4444 from other countries from 8:00 a.m. to 8:00 p.m. Eastern Standard Time, Monday through Friday (except U.S. federal holidays).
• Follow us on Facebook.

Should probably put out a similar notice out to all residents of the US regarding Election Day?

I don't know, I think everything in the US will be fine. The trouble makers are calming down a little due to the poor performance of their candidate of late. I guess she could encourage more violence. Of course there will be some disillusioned lefties who might still act up after the election but most are starting to see the writing on the wall.

The demonstration happened with a couple thousand people .... no violence.