The U.S. flag is never flown at half staff at four locations 1. the moon 2. USS Arizona (Pearl Harbor) 3.the statue of marines at Iwo Jima, what is the fourth location?

Half staff flag notifications

http://us.halfstaff.org/

Flag Laws and Regulations
By Executive Order, the flag flies 24 hours a day at the following locations:
http://www.ushistory.org/betsy/flagetiq.html#3

The flag should be displayed on all days, especially on Memorial Day (half-staff until noon), the last Monday in May.
http://www.ushistory.org/betsy/flagetiq.html#3

All the sites about the American flag say there are only two places the American flag is never flown at half-staff. The Moon and In Battle. However, they go on to contradict themselves (I think) by mentioning a third. Everywhere after 12:00 noon on Memorial Day.
http://www.ushistory.org/betsy/flagetiq.html

This site says different:

• Fort McHenry National Monument and Historic Shrine, Baltimore, Maryland
• Flag House Square (Mary Pickersgill's "Star Spangled" House), Baltimore Maryland
• United States Marine Corp Memorial (Iwo Jima), Arlington, Virginia
• On the Green of the Town of Lexington, Massachusetts
• The White House, Washington, DC.
• Washington Monument, Washington, DC.
• United States Customs Ports of Entry which are continually open
• Grounds of the National Memorial Arch in Valley Forge State Park

https://www.crwflags.com/fotw/Flags/us_24hr.html

It keeps the American flag at Arlington at half-staff all day, every day except weekends.
http://www.arlingtoncemetery.com/every-day.htm

This website has many places listed .. including The White House, Arlington Cemetary and The Tomb of the Unknown Soldier (all not lowered as they are already there to commemorate the dead). Another flag is the one at The Alamo which is nailed on and therefore never lowered to half staff.

www.fotw.ca/flags/faq3.html