Google has updated its documentation that contains advice for improving your local ranking on the search engine.
There's a section about "prominence" that has some new language in it, and that seems to be the most significant change. Here's what the section says now:
Prominence refers to how well-known a business is. Some places are more prominent in the offline world, and search results try to reflect this in local ranking. For example, famous museums, landmark hotels, or well-known store brands that are familiar to many people are also likely to be prominent in local search results.
Prominence is also based on information that Google has about a business from across the web (like links, articles, and directories). Google review count and score are factored into local search ranking: more reviews and positive ratings will probably improve a business's local ranking. Your position in web results is also a factor, so SEO best practices also apply to local search optimization.
The key part to take note of here is the one about Google using links, articles, and directories from across the web for prominence.