Why Health Insurance Costs Vary So Much by County

How Geographic Rating Works

Under the ACA, each state divides its territory into geographic rating areas - groups of counties where insurers set uniform base rates. Within a rating area, all enrollees of the same age and tobacco status pay the same premium for the same plan. The ACA limits the factors that can affect your premium to just four: age, tobacco use, geographic location, and family size. Race, gender, health history, and pre-existing conditions cannot be used.

Geographic rating areas are the mechanism through which local cost differences flow into your premium. A rating area anchored by an expensive hospital system or a single dominant provider network will have higher base rates than one with competitive hospital markets and multiple provider systems.

The Competition Effect

The single strongest predictor of premium levels in a county is the number of insurers competing. Research from the Kaiser Family Foundation and others has consistently found that each additional insurer in a marketplace is associated with lower benchmark Silver premiums - often by 3-7% per additional carrier.

The difference between a monopoly market and a competitive one can be dramatic. Counties with a single insurer often pay 15-30% more than comparable counties with four or five carriers. In extreme cases, the gap is even wider. This is one reason why the cheapest and most expensive counties in the country can be in the same state, one has robust competition, the other has a single carrier.

Browse our issuer profiles to see which carriers serve your area and how many operate in your county. Our county pages show the number of issuers alongside average premiums so you can see the relationship directly.

Issuer-count tiers and benchmark premium impact (KFF analysis)

Kaiser Family Foundation's annual Marketplace tracker quantifies the issuer-count premium effect across rating areas. The relationship is consistent enough to use as a rule of thumb when reviewing a county:

Pattern derived from Kaiser Family Foundation Marketplace Tracker reporting (kff.org/health-reform/state-indicator/marketplaces). Actual deltas vary by state.

Provider Costs and Hospital Market Power

Healthcare provider consolidation is a major driver of premium variation. When a single hospital system dominates a region, it has significant leverage in negotiations with insurers, it can command higher reimbursement rates because insurers cannot build a viable network without it. These higher provider costs flow directly into premiums.

Rural areas are especially affected. Many rural counties have only one hospital, which becomes the de facto monopoly provider. The insurer has no alternative, so it pays whatever the hospital demands. In contrast, metropolitan areas with multiple competing hospital systems often see more moderate provider costs and, in turn, lower premiums.

Risk Pool Dynamics

The health profile of the people who enroll in a county's marketplace affects premiums for everyone. If a county's marketplace disproportionately attracts older or sicker enrollees (while healthier people opt out or get employer coverage), the risk pool becomes more expensive. Insurers set next year's rates based on this year's claims experience, so an unhealthy risk pool drives premiums up, which can push more healthy people out, creating a cycle.

The ACA's risk adjustment program partially addresses this by transferring funds from insurers with healthier enrollees to those with sicker enrollees. But it does not fully equalize costs across counties. Small counties are particularly vulnerable to risk pool volatility because a handful of high-cost enrollees can meaningfully shift the average.

Rural vs. Urban: The Persistent Gap

Rural counties face a compounding set of disadvantages: fewer insurers, fewer providers with more market power, smaller and often older populations, and higher per-capita healthcare costs. The result is that rural Marketplace premiums average 10-25% higher than urban premiums in most states.

However, subsidies partly offset this gap for lower-income enrollees. Because Premium Tax Credits are calculated relative to the benchmark Silver plan in your county, a high-cost county produces a larger subsidy. A household at 200% FPL in a high-premium rural county may pay the same out-of-pocket as an identical household in a cheap urban county, the subsidy absorbs the difference. The cost gap matters most for people above 400% FPL who receive no subsidy and pay the full unsubsidized premium.

How to Use PlainHealthPlan's County Data

PlainHealthPlan tracks average premiums by metal tier for over 2,000 counties across 30 FFE states. To understand your county's position:

• Start on the state page for your state, see statewide averages, issuer counts, and year-over-year premium changes.
• Drill down to your county page - see Silver, Bronze, and Gold averages, the number of issuers, and 5-year premium trends.
• Compare your county to neighboring counties, the premium spread within a single state can be revealing.
• Check the issuer pages - see each carrier's footprint, plan types, and average pricing.

Understanding where your county falls relative to the national and state average helps you set realistic expectations for what insurance will cost, whether subsidies will cover the gap, and whether it makes financial sense to consider a move.