What the flag code actually requires at night
Does the flag have to be lit after dark?
Only if it stays up. The flag is customarily displayed from sunrise to sunset. If it is flown 24 hours a day, federal law requires that it be properly illuminated during the hours of darkness. The statute does not define "properly" in wattage or lumens — it sets a functional standard, not a specification.
The statute, in full
The relevant provision is 4 U.S.C. § 6(a). It reads: "It is the universal custom to display the flag only from sunrise to sunset on buildings and on stationary flagstaffs in the open. However, when a patriotic effect is desired, the flag may be displayed 24 hours a day if properly illuminated during the hours of darkness."
Two things follow from that sentence. Daytime display is the custom rather than a requirement, and continuous display is permitted — conditionally. The condition is the lighting.
What "properly illuminated" means in practice
Nothing in the United States Code sets a wattage, a lumen count, or a colour temperature. The generally applied test is whether the flag is recognisable to a casual observer at a reasonable distance — a functional standard rather than a measured one.
Where a measured figure is wanted, the industry reference is the Illuminating Engineering Society guidance commonly cited at 10 horizontal and 3 vertical footcandles in the flag area. That is a design guideline, not law, and the distinction is worth keeping straight when specifying an installation.
Is it enforceable?
The flag code is directive rather than penal for private citizens — it prescribes conduct without attaching a penalty to most of it. That is a fair summary, and it is also the reason the question comes up more often for institutions than for households.
Public bodies, schools and government buildings tend to treat the code as a standard they are expected to meet, and contracts and specifications frequently incorporate it directly. For those buyers the question is rarely "must we" and usually "does this installation actually comply".
Where state law adds to it
A number of states require the flag to be displayed at public schools and public buildings, and some require additional flags on particular days. Those requirements govern display; the federal condition on overnight display still applies on top of them.
Requirements vary by state and change. Confirm the current rule for your jurisdiction rather than relying on a general summary — including this one.
Common questions
- Can I fly the flag at night without a light?
- The custom is to display it from sunrise to sunset. Continuous display is what triggers the illumination condition, so taking it down at dusk avoids the question entirely.
- How bright does the light need to be?
- No federal minimum exists. The practical test is whether the flag is clearly recognisable at night from a reasonable distance. Where a specification is needed, designers commonly reference 10 horizontal and 3 vertical footcandles, which is industry guidance rather than law.
- Does solar lighting satisfy the requirement?
- The statute is indifferent to the power source. What matters is whether the flag is properly illuminated through the hours of darkness, which makes run time and output in poor weather the questions worth asking of any solar product.
- Who enforces the flag code?
- For private display it is largely directive rather than penalty-backed. For public institutions it is commonly written into specifications and contracts, which is where it acquires teeth.
Sources
Specifications, quantities, lead times
Schools, municipalities and government buyers generally need a written quote to put in front of somebody else. Ask and you will get one.