Which US Industries Have the Biggest Knowledge Graph Gap? (2026)

When someone asks ChatGPT, Claude, or Perplexity for a lawyer, a medical clinic, or a real estate agent, the answer comes from knowledge graphs like Wikidata—not from indexing every website. Most US local businesses are not in those graphs yet. This post compares the knowledge graph gap across three local-business verticals using live Wikidata data and explains which industries are furthest behind and what that means for Generative Engine Optimization (GEO) and agencies.

Data as of March 2026. Numbers are from SPARQL queries against the public Wikidata Query Service. Our multi-industry coverage script produces these counts and writes to reports/wikidata-multi-industry-coverage.json; you can run it to reproduce or refresh the snapshot.

The numbers: US local businesses in Wikidata (with website)

So in raw terms: law firms have the most US entities with a website in Wikidata (317), followed by real estate (52) and medical clinics (35). Hospitals are included only for context—US hospitals in Wikidata number in the thousands, which makes the clinic gap especially stark.

Where is the gap biggest?

• Medical clinics vs hospitals: There are 3,327 US hospitals in Wikidata but only 35 US medical clinics (with website). So by proportion, clinics are the most under-represented: the knowledge graph is heavily skewed toward hospitals, and the vast majority of independent and small-to-medium medical practices are absent. For GEO and agencies, that means clinic clients have the most upside and the least in-graph competition.

• Law firms and real estate: Both have hundreds of thousands of businesses in the US in the real world; 317 and 52 in Wikidata respectively is still a tiny slice. Law firms have more entities than real estate in the graph today, but both verticals have a very large gap. Agencies serving either can use the same story: "Almost none of your competitors are in the data source AI assistants use."

• Takeaway: The biggest relative gap is for medical clinics (vs hospitals). The biggest absolute opportunity for "get into the knowledge graph" messaging is across all three—law, medical, real estate—because the majority of local businesses in each vertical are still missing from Wikidata.

Why this matters for GEO and agencies

1. Prioritization: If you're an agency or a GEO platform, clinics (and other SMB healthcare) may offer the strongest "gap" narrative: few entities in the graph, clear comparison to hospitals, and high demand for "find me a doctor/clinic" in AI search.
2. Sales and strategy: Use the table above in pitches. "Here’s how many [law firms / clinics / real estate companies] in the US are in the knowledge graph that ChatGPT and Perplexity use. Your clients are either in that set or they’re invisible for AI-driven discovery."
3. Product and positioning: GEO solutions that publish businesses to Wikidata and monitor AI visibility are directly addressing this gap. The industries with the largest gaps are the ones where "get listed, get tracked" has the most room to grow.

Methodology

Data comes from the public Wikidata Query Service. Definitions (instance of, country United States P17=Q30, official website P856) match our multi-industry coverage script and the report consumed by For Agencies:

• Law firms: instance of law firm (Q613142), US, has website.
• Medical clinics: Health care facility or business with medical specialty, US, has website, excluding hospitals (Q16917).
• Real estate companies: instance of real estate company (Q1660104), US, has website.

For industry-level detail and SPARQL logic, see Wikidata Local Business Coverage: What SEO Agencies Need to Know, US Legal Firms in Wikidata: Coverage Report February 2026, and US Medical Clinics in Wikidata: Coverage Report February 2026.

Next step

See AI Visibility for SEO Agencies for the latest coverage table and how to add knowledge graph publishing and AI visibility monitoring as a service for your clients.

Internal links

• Wikidata Local Business Coverage: What SEO Agencies Need to Know (2026)
• US Legal Firms in Wikidata: Coverage Report February 2026
• US Medical Clinics in Wikidata: Coverage Report February 2026
• For Agencies
• Law Firm Visibility in ChatGPT
• Medical Clinic Visibility in ChatGPT
• Real Estate Agent Visibility in ChatGPT