The United States is not one personal injury system, it is fifty-one. Each state, plus the District of Columbia, maintains its own tort law, statutes of limitation, fault-allocation rule, and damages caps. There is no national quantum guideline. A claim that would be worth $400,000 in California can be worth zero in Maryland on the same facts because Maryland still applies pure contributory negligence.
For practitioners and claimants, that means three things matter most: which state's law applies, what comparative-fault rule that state uses, and what statutory cap (if any) bites on the heads of damages at issue. Country-page coverage here states the framework and links to the state pages where bands live.
On top of state law sit several federal overlays, the Federal Tort Claims Act for claims against the federal government, the Federal Employers' Liability Act for railway workers, and the Jones Act for seafarers. Where one of those applies, the federal regime, not the state's default tort rules, controls.