Section 333 of the US Code makes things pretty clear.

Only state governors can decide to lower the flag to half staff, according to US Code.

The US Code is also available online and searchable by word or phrase.

This has created a situation not duplicated anywhere else in the entire U.S. Code.

I can recite the U.S. Code in my sleep, thank you.

The U.S. Code has a number of regulations concerning railroads.

In 1954, various acts were codified into Title 13 of the US Code.

U.S. Code of law explicitly limits the total number of general officers who may be on active duty.

How do I get to an online copy of the U.S. Code?

Also, date of related changes in title 17 of the U.S. Code.