The Google Map Pack — the block of three local business listings with a map that appears at the top of Google search results for local queries — receives more clicks than any other section of the search results page for local searches. For a patient searching “clinical trial near me” or “diabetes study [city],” the three sites in the map pack are the first and often only options they consider. Understanding how Google selects these three is the foundation of local SEO for research sites.
The Three Factors Google Uses to Rank Local Results
Google’s local ranking algorithm uses three primary factors: relevance, distance, and prominence. Relevance measures how closely your GBP and website match the search query — which is why your profile completeness, categories, services, and description matter. Distance measures how close your location is to the searcher or the location specified in the search. Prominence measures how well-known and trusted your business is — driven by review count and rating, website authority, mentions in directories and news, and the activity level of your GBP.
You cannot change your distance from searchers, but you can significantly improve your relevance and prominence scores. Most research sites that fall outside the map pack are not failing on distance — they are failing on relevance (incomplete or poorly optimized profiles) and prominence (few reviews, low website authority, inactive GBP).
Building the Relevance Signals That Secure Map Pack Placement
Relevance signals come from both your GBP and your website. On your GBP, completeness is the foundation: every field filled, every category selected, every service listed, and a keyword-rich description. On your website, Google looks for consistent NAP (name, address, phone) data matching your GBP exactly, local content that mentions your city and surrounding area naturally, and structured data markup confirming your location and business type.
The consistency of your NAP data across all online directories is also a relevance signal. Your address as it appears on your GBP should appear identically on your website, on Yelp, on Healthgrades, on Facebook, on your ClinicalTrials.gov listing, and on any other directory where you have a presence. Even minor inconsistencies — “Suite” vs “Ste,” “Street” vs “St” — can create confusion in Google’s data model and reduce your relevance score for local searches.
Building Prominence to Pull Ahead of Competitors
Prominence is where active management makes the biggest difference. Review velocity — the rate at which you are receiving new reviews — is a strong prominence signal. A site receiving two to three new Google reviews per month consistently outperforms a site with the same total review count that received all of its reviews two years ago and has been inactive since. Build a systematic review request process and treat ongoing review generation as a core operational activity.
Off-profile prominence signals include backlinks from local healthcare organizations, mentions on local news sites, listings on authoritative medical and clinical research directories, and engagement with your website from local visitors (measured by Google through Chrome and search activity data). Getting listed on ClinicalTrials.gov with your address and contact information, being mentioned in local hospital or university newsletters, and earning placement on patient advocacy organization resource lists all build the prominence signals that support map pack placement and retention.
Map pack position is not static. A competitor that starts optimizing their GBP aggressively can push you out within weeks. Monitor your map pack position monthly using a local rank tracker and respond to position changes with targeted improvements in the factor area — relevance, prominence, or activity — that data suggests is falling behind.