Source: https://www.todayifoundout.com/index.php/2017/05/surprising-number-legal-rules-pertaining-displaying-united-states-flag/
Timestamp: 2019-04-24 00:02:56+00:00

Document:
Fifty white stars on a field of blue (one for each state) and 13 horizontal stripes, alternating red (7) and white (6) for the original 13 colonies, the U.S. flag is a revered symbol by many of the nation. And in recognition of the honored place Old Glory holds, in 1947, Congress passed a series of laws, specifically proscribing how the flag should look, be cared for and respected.
Found near the beginning of the codified version of the statutory laws of the United States (called the U.S. Code) in Title 4 (out of 54), the provisions relating to the flag are numerous and detailed. For example, the Code has specific rules for when civilians can display the flag, and these allow that it may be set out for 24 hours at a time, should be raised quickly and lowered “ceremoniously,” and unless an all-weather flag, should not be displayed during bad weather. 4 U.S.C. § 6.
In addition, two types of institutions, schools and polling places, should always display a flag when operating. Id.
There are also rules about how to display the Flag in a procession (like a parade), and it should either be to the right or in front of a line of flags, and should never be placed on a parade float except on a staff. 4 U.S.C. § 7. It also should not be draped over the hood, sides, or back of a car, but may be “fixed firmly to the chassis or clamped to the right fender.” Id.
Except for church services for Navy personnel when a church pennant may be hung above it, the Flag should never be displayed below another one, other than at the United Nations headquarters. Id.
On that note, while the Code, which explicitly notes, “No disrespect should be shown to the flag of the United States of America” may prohibit such things as desecration of the Flag, its use in advertising, or on temporary merchandise like napkins (flag napkins and paper plates commonly found at any 4th of July party). etc., for various reasons, those sections are not enforced. For example, the Code’s § 3 was specifically identified in a 1925 Attorney General Opinion to apply only to activities within the District of Columbia. 34 Op.Atty.Gen. 483.
However, even if § 3, like § 8, did apply throughout the nation, it’s doubtful either law could ever really be enforced, as activities related to the Flag have been interpreted by the United States Supreme Court as being protected “speech” under the First Amendment, and, therefore, not subject to punishment by the government. See Texas v. Johnson and United States v. Eichman (holding flag burning as Constitutionally-protected speech).
The Pledge of Allegiance is also set out in the Code, which provides that only “men” not in uniform should remove their “non-religious headdress with their right hand” when reciting it. 4 U.S.C. § 4. All, however, are instructed to put their right hands over their hearts when reciting it. It should also be noted that those members of the military in uniform should not recite the words, but instead remain silent, giving the military salute.
4 U.S.C. § 1 et seq.
Surely, that should be “prescribing”???

References: § 6
 § 7
 § 3
 § 3
 § 8
 v. 
 v. 
 § 4
 § 1