Here are widely-recognized top SEO agencies serving North America (mix of large, full-service firms and specialist SEO shops). I pulled these from recent industry directories and agency-ranking sites — links shown as citations so you can verify specialties, locations, reviews and pricing.

Top picks (short descriptions + why they’re notable)

1. Ignite Visibility — full-service digital marketing and SEO; regularly ranked among top U.S. SEO firms for enterprise and mid-market SEO. (granwehr.com)
2. Victorious — SEO-focused agency known for data-driven organic growth and transparent reporting; frequently appears on “best SEO” lists. (granwehr.com)
3. WebFX — large U.S. agency with extensive SEO, content and conversion optimization capabilities and many client case studies. (granwehr.com)
4. Coalition Technologies — enterprise and e‑commerce SEO + web development; often listed among top-performing SEO shops. (granwehr.com)
5. SmartSites — New Jersey-based agency with SEO + PPC focus; appears on multiple agency ranking lists for North America. (DesignRush.com)
6. HigherVisibility — SEO-first agency (local and national SEO) with strong track record in U.S. markets. (DesignRush.com)
7. SEMrush Agency Partners (selected firms) — SEMrush’s agency directory highlights vetted SEO specialists across North America (useful to find vetted, tool-savvy agencies). Example entries include Azuro Digital (Canada), Algorank (Canada), Sixth City Marketing (U.S.). (agencies.SEMrush.com)
8. Straight North — B2B and lead-generation focused SEO and PPC agency commonly ranked in Clutch-style lists. (granwehr.com)
9. Big Leap — SEO and content for growth-focused brands (appears on aggregated “top SEO” lists). (granwehr.com)
10. Local/Canada-specialist options — SEMrush and regional directories list Canadian-focused firms (examples: Azuro Digital, Algorank, dNovo Group) if you prefer agencies familiar with Canadian search/local requirements. (agencies.SEMrush.com)

How to pick the best one for you (quick guidance)

• Match industry experience: prefer agencies that show case studies in your vertical.
• Scale & services: choose a specialist SEO shop for pure organic work or a full-service agency if you also need CRO, paid media, content, or dev support.
• Reporting & KPIs: confirm what KPIs and cadence of reporting you’ll get (rankings, traffic, conversions, revenue).
• References & case studies: check recent client outcomes and ask for references for similar-sized clients.
• Budget & contracts: clarify price range, minimums, and contract length — directories usually show starting ranges. (See agency profiles for pricing examples.) (agencies.SEMrush.com)

If you’d like, I can:

• Narrow this to the top 5 agencies specifically for Canadian businesses; or
• Find agencies that specialize in e‑commerce, B2B, or local SEO in a particular province or U.S. state and give contact/portfolio links.

Which would you prefer?