Geographic evidence lab

State comparison studio

Compare state concentration measures within one product and geographic framework. Selected jurisdictions retain their periods, sources, and interpretation limits.

Universe51Jurisdictions

Measures3Comparable signals

Selected4Shareable set

Comparable here

Every row is a 2024 state observation for the same ACA-regulated individual health insurance market, published through one KFF methodology.

Boundary still matters

These measures screen one insurance market. They do not rank state economies, employer coverage, consumer welfare, or legal liability.

Selection console

Choose two to four jurisdictions

Every selection retains the same individual-insurance market, KFF source, 2024 vintage, and metric definitions.

4 / 4

2 Census regions represented.

Selected

42 regions

High HHI

0At or above 2,500

Majority leaders

0Largest insurer at 50%+

Thin rivalry

0Three or fewer above 5%

Comparable state field

Market HHI across selected states

Bars share the 51-jurisdiction observed range. The benchmark marker is the published U.S. value.

Selected jurisdictionsHigher = more concentrated

Pressure lead: Michigan at 2,413. U.S. benchmark: 3,650.

Active state dossier

California

Moderately concentrated

West rank #9 on the higher-pressure ordering.

2,389National rank #41

U.S. benchmark

3,650-1,261 state delta

West avg

3,523-1,134 state delta

Benchmark matrix

Published measures and national deltas

Ranks follow pressure direction: higher HHI and leader share rank first, while fewer meaningful rivals rank first.

Jurisdiction	Region	Market HHI	Largest insurer share	Insurers above 5% share	Profile
CaliforniaCA / Moderately concentrated	West	2,389#41 / -1,261 vs U.S.	33%#41 / -15% vs U.S.	5#36 / +1 vs U.S.	Open
ArizonaAZ / Moderately concentrated	West	2,410#40 / -1,240 vs U.S.	30%#45 / -18% vs U.S.	4#28 / 0 vs U.S.	Open
MichiganMI / Moderately concentrated	Midwest	2,413#39 / -1,237 vs U.S.	31%#44 / -17% vs U.S.	5#36 / +1 vs U.S.	Open
IdahoID / Moderately concentrated	West	2,353#42 / -1,297 vs U.S.	32%#42 / -16% vs U.S.	4#28 / 0 vs U.S.	Open

Evidence contract

One market, one source, one vintage

Market: U.S. individual health insurance
Coverage: 51 jurisdictions / 2024
Publisher: KFF
Selected packet: CA / AZ / MI / ID

This geography layer describes the ACA-regulated individual health insurance market using KFF's 2024 state-level measures. It does not measure a state's overall economy, employer-sponsored insurance, or a legal market definition.