How We Build the Ad Competition Index and Every County Figure
Every number on our county pages comes from public U.S. Census Bureau data and is computed the same way for every county. This page explains the definitions, the formulas and what the numbers cannot tell you.
The index
What the Ad Competition Index Measures
The index answers one question: for the kinds of local businesses that rely on advertising to win customers, how crowded is this county compared with other counties? It is a measure of the number of local businesses competing for residents, not of what any ad costs.
Step 1, categories. We use twelve ad-heavy categories, identified by NAICS code: law offices (541110), plumbing, heating and air-conditioning contractors (238220), roofing contractors (238160), electrical contractors (238210), residential remodelers (236118), landscaping services (561730), dentists (621210), physicians offices (621111), real estate agents and brokers (531210), insurance agencies and brokerages (524210), general automotive repair (811111), and accounting and CPA firms (541211).
Step 2, density. For each category we take employer establishments from the Census Bureau's County Business Patterns (2022) and divide by the county's 2023 population estimate, giving locations per 10,000 residents. A category with no row in the Census table for a county is treated as zero.
Step 3, percentile. Within each category we rank every U.S. county with 20,000 or more residents (1,822 counties) and record the share of those counties with a strictly lower density. A county at the 90th percentile in law offices has more law offices per resident than 90% of the counties compared.
Step 4, the score. The index is the simple average of the twelve category percentiles, from 0 to 100. A score near 50 is a typical county. Counties under 20,000 residents are not scored because per-resident densities are too unstable at that size.
Other figures
How the Other Numbers Are Calculated
- Crowding versus a typical county: a category's locations per 10,000 residents divided by the median of that category across the 1,822 counties. 1.0x is typical.
- Change 2017 to 2022: percentage change in employer establishments in the category (or, for the headline measure, in all twelve combined) between the 2017 and 2022 County Business Patterns.
- Locations with 20+ staff: establishments in the Census size classes of 20 employees and above; the share is that count divided by all establishments in the twelve categories.
- New-home permits: housing units authorized by building permits from the Census Bureau's Building Permits Survey, per 10,000 residents for 2025, and a same-months comparison for the current year.
- Look-alike markets: for the 400 markets we cover, the six nearest on a standardized combination of population (log), income, Ad Competition Index, population growth, share of residents outside incorporated places and permits per resident.
- Percentile bars on each page: the share of the 1,822 counties with a lower value (or, where we say "slower" or "lower", the share with a higher one).
Sources
Where the Data Comes From
- U.S. Census Bureau, Population Estimates, Vintage 2023 (county and incorporated-place totals)
- U.S. Census Bureau, County Business Patterns, 2022 and 2017
- U.S. Census Bureau, Small Area Income and Poverty Estimates, 2023 (median household income)
- U.S. Census Bureau, Building Permits Survey (county annual and year-to-date files)
- U.S. Census Bureau, 2023 Gazetteer (county centers, used for distances)
State advertising rules, where shown, link to the statute, regulation or regulator that publishes them, and each block states when we last checked it.
Limits
What These Numbers Cannot Tell You
- They are not ad costs. The index counts businesses. What a click costs is set in an auction that depends on keywords, ads, landing pages, time of day and more. We do not publish cost-per-click or cost-per-lead figures.
- They are not our results. We do not use client account data or publish GetPhound campaign performance on these pages, because every business and market differs.
- Establishments are not advertisers. Some of the businesses counted never advertise; others advertise into the county from elsewhere. Sole proprietors without employees are not in County Business Patterns.
- Connecticut is different. The Census Bureau replaced Connecticut’s eight counties with nine planning regions in its newest files, but County Business Patterns for 2022 and the Building Permits Survey from 2023 on use them while most people still search by county (“Fairfield County”, “Hartford County”). For Connecticut we therefore use the historic counties with 2021 population and income estimates and 2021 business counts (compared with 2017), and we leave out permits. Pages say so.
- Data has a lag. Business counts are from 2022 and population from 2023. We note the year beside each figure and rebuild the data when the Census Bureau releases new files.
Found a mistake? Email hello@getphound.com and we will check it against the source.
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