How we source this

Most pages about state car seat rules are assembled from other pages about state car seat rules, and the original statute is three or four copies back. This page describes what we do instead, including the parts that make the site look less complete than its competitors.

Statute first, state agency second, nothing else

Every required field is sourced to the state statute that sets it, or — only when the statute itself does not set a number — a page published by the state agency responsible for child passenger safety. Each state has its own list of allowed source hosts indata/source_domains.json; a URL that is not on that state's list cannot be used as a source, no matter how authoritative it looks. Law firm articles, car seat retailer pages and comparison sites are never a source. They are leads at most, and every value they suggest is re-read at the official source before it is published.

An unsourced value is not published

This is enforced by the build, not by discipline. Every required block — stages, front-seat rule, penalties, exemptions — must carry a source URL, a source name and the date it was verified, or the build fails. There is no path through the code that puts an uncited figure in front of a reader.

How IIHS and GHSA are used

The IIHS child safety seat table and the GHSA child passenger safety table are useful for finding what we might have missed, so every state's data is cross-checked against both. When our reading of the statute disagrees with IIHS or GHSA, we re-read the statute section named in our note. If the statute still supports our value, the statute wins and the value stays — even when IIHS and GHSA agree with each other. IIHS and GHSA are never used as a source for a published value; they only tell us where to look again.

What "not addressed in statute" means

A field can read "not addressed in statute" instead of a number or a yes/no. That happens only after someone has read the relevant section in full and confirmed it says nothing about that field — for example, many states set no minimum age for moving a child to the front seat. It is not a stand-in for "we could not find this" or "the state agency was unreachable." When a source cannot be reached at all, the field is left out of the build entirely and the state is held back until someone can confirm it by hand, rather than shown with a guess.

How the age and weight limits are read (exit logic)

Statutes describe when a child can leave a car seat stage in different ways, and a single number cannot always capture that. Each stage on each state page is tagged with how its limits combine:

• All conditions — the child must meet every listed limit before leaving the stage (for example, "under two years or under 30 pounds" is read as requiring both age and weight before the child may move on).
• Any condition — meeting a single listed limit is enough, which covers "whichever comes first" wording directly.
• Compound — the statute mixes conditions in a way neither of the above can express on its own, such as an age-and-weight test combined with an independent height test. The full condition is written out in plain terms on the page rather than forced into a single number.
• Text only — the statute uses a fit test instead of a number, such as requiring a seat belt to fit properly rather than naming a height. The rule text is shown as written; there is no number to project.

We show the statute's own wording first on every stage, and the numeric limit next to it as a comparison aid — the wording is what actually governs, not our projection of it.

How the booster-age ranking works

The state comparison ranks states by the age at which their statute requires a booster seat. A state is included in that ranking only when all three are true: the booster stage is required by statute, its limits combine as "all" or "any" (not a compound condition or a fit test), and the statute sets a numeric age. States that meet all three are ranked from oldest required age to youngest, with tied ages sharing a rank.

A state is left out of the ranking, with a reason shown on its page, when any one of these applies: the statute does not address booster seats at all; the statute does not require a booster; the booster stage is governed by a fit test rather than a number; the statute combines conditions in a way a single age cannot represent; or the statute sets a weight or height limit for the booster stage but no age limit. A state left out of the ranking is not treated as having no booster law — the reason on its page says exactly which of these applies.

Verified dates and daily rebuilds

Every sourced block carries the date it was last verified against the statute, shown on the page. When a legislature has passed a change that is not yet in force, the page shows the current value as the value in effect today, with the enacted change and its effective date shown alongside it. The site rebuilds every day, so once that date arrives the new value takes over automatically without anyone needing to edit the page by hand.

NHTSA and AAP recommendations

The recommendation shown next to each stage comes from the National Highway Traffic Safety Administration and the American Academy of Pediatrics, cited and dated the same way state law is. These are safety recommendations, not law — a state's legal minimum can be, and often is, lower than what NHTSA or the AAP recommends. The two are shown side by side and never merged into one figure.

Some official sites block us

A number of state legislature and agency sites block automated access. When that happens we still read the statute — through an archived capture or a text-only proxy of the same official page, checked against the original — rather than substituting a secondary source. The citation on the page always points at the original official URL, never the workaround.

Corrections

Fifty-one jurisdictions amend their statutes continuously and we will sometimes be behind. Stale figures, dead links and states we have not re-verified recently are all worth reporting — send them through thecontact page. A correction that names the statute section is the fastest kind to act on.