On September 1, 2016, Google quietly released a new update. It's nicknamed "Possum" by the SEO community.

Possum, unlike most other updates, affects only local search results. That means if you're trying to rank #1 for a keyword and you aren't concerned about location, Possum probably won't affect you one bit.

On the other hand, if you're trying to push a mom and pop shop to the top of the local 3-pack for a particular region, then you need to know what happened with the Possum update.

You might think that the best way to learn about Possum is to get the info directly from Google. Unfortunately, Google won't be very forthcoming at the moment.

That's because, as of this writing, Google isn't even acknowledging that Possum even happened.

So how do we know about Possum? Savvy Local SEOs noticed behavioral changes in search results. They've compiled their observations into a list and shared them with the world.

Here's what they've discovered.

1. It's Easier to Rank Businesses That Just Miss the Mark

In the past, there was quite a bit of wailing among Local SEO professionals who had trouble ranking clients for a specific city if their business address was just outside the city limits.

For example, if a dentist was located very close to the border of Chicago, but still outside of Chicago, then that poor dentist would have trouble ranking in the local 3-pack for a search term like "dentist chicago."

That didn't seem right to a lot of small business owners because, after all, businesses that are in close proximity to a city often have customers that live in the city. It just makes sense that they should be able to reach them via local search results.

But, for a while anyway, Google wouldn't budge. Businesses simply couldn't rank in local results if their address wasn't in city limits.

Thanks to Possum, that's all changed.

Why? Because now the algorithm uses a proximity test to determine if the business qualifies to rank. So if a business is close to a city, it can rank with that city name.

In other words, the update actually makes it easier to rank businesses. That's a switch from a lot of algorithm updates that we've seen in the past that tend to push listings lower in the search engine results pages (SERPs).

2. It Filters Based on Address

Google doesn't like to show its users the same listing over and over again in the search results. That's especially true in local search.

Some businesses, though, have multiple listings for the same site.

For example, a doctor's office will often employ multiple physicians, each with his or her own personal practice. Some law firms might have multiple departments, each with a unique Google My Business (GMB) page.

In the past, Google filtered out duplicate entries like that based on phone number or domain name. Now, Possum takes things a step further and filters them out based on the physical address of the listing.

So, for the examples above, a local searcher would only see one doctor's name from that office and one legal department listing from that law practice.

It should be noted, though, that the other listings aren't eliminated completely. They're just pushed down lower in the rankings.

3. Location Matters

The new Possum update makes local search results dependent on the searcher's location.

In the past, search results were weighted more heavily towards the search terms. Now, Google uses the IP address of the person performing the search to provide more accurate results in the local 3-pack.

It's important to understand that if you're doing any kind of Local SEO for another business. Your QA team should test your work as a user within the region of the business and not simply test it by Googling the business name and its location.

Also, the more a user moves away from a specific location, the more that the Google Map zooms out. As the map zooms out, business listings located in the zoomed-in version of the map are likely to drop. That's true even if the location name is included in the search query.

Why does location suddenly matter so much? One word: mobile.

Remember, Google is going out of its way to offer an outstanding experience for the mobile community. The location-sensitive piece of the update seems to be in line with that strategy.

4. It's Sensitive to Slight Keyword Changes

There's another Possum change that's going to affect how you test your Local SEO efforts. Now, even the slightest variations in keywords can produce different search results.

For example, if a searcher Googles something like "podiatrist phoenix," that could produce completely different results than a search term such as "podiatrist in phoenix, arizona" or "phoenix podiatrist."

It's not clear what the algorithm is trying to accomplish by being so finicky about search terms, but it's important to understand that you'll need to test a wide variety of word variations, even if they seem very similar, when testing Local SEO.

5. It Ignores the Organic Filter

Prior to Possum, some local listings didn't appear in the results because they linked to a site that was filtered in the organic results. Now, that's no longer the case.

As we've seen, Google tries to remove duplicates in its search results. That doesn't just apply to local search results, though. It also applies to organic results.

The problem before the latest algorithm change is that some local listings would link to a site that was filtered from the organic results. Because of that, Google would filter that listing from the local results.

Understandably, that didn't go over to well with many members of the local business community.

Fortunately, Google heard their pleas. Now, the local search filter operates independently of the organic search filter.

Wrapping It Up

Since Google still hasn't even fessed up about the Possum update, it's quite likely that it isn't even finished. That means we could see more changes in the future. For now, though, it's important that SEOs understand how Possum affects their local marketing efforts. If you want to learn more about local SEO here is a video covering the basics.