Why does Google continue crawling 301 redirected URLs for over a year?

How does Google handle 301 redirects over time?

The logic is that a 301 redirect indicates a permanent move: the old URL disappears, and the new one takes its place. In practice, it's more nuanced. If external backlinks continue pointing to the old address, Googlebot still visits it, because its entry point remains this outdated URL.

After a few visits, Google understands the situation and switches the canonical to the new URL. What does this mean? The engine now associates ranking signals — authority, anchors, context — with the final destination, not the starting point. The old URL becomes just a technical relay.

Why do these URLs still appear in site: searches?

Let’s be honest: the site: commands are not an exact reflection of Google's index. They show a set of URLs known to the engine, but not necessarily those that contribute to ranking. An old redirected URL may show up in this result because Google retains it in memory as a historical entry point.

In contrast, the version that is actually indexed — the one appearing in the standard SERPs — is indeed the new one. It is the one that holds the content, the metadata, and the positioning potential. The old one is just a ghost in the logs.

What impact does this have on crawl budget and site performance?

The crawl budget is not infinite. If Googlebot spends time visiting hundreds of redirected URLs, it dedicates less time to strategic pages. On a small site, the impact is negligible. On a platform with thousands of backlinks pointing to migrated URLs, it can stall.

The obvious solution — cleaning up the inbound links — is rarely 100% applicable. Some backlinks are on third-party sites that we do not control, others are in web archives or abandoned forums. The problem thus persists over time.

• Old crawled URL: Google continues to visit it as long as there are external links pointing to it.
• Canonical switched: After a few crawls, the engine associates signals with the new URL.
• Site: appearance: The old URL may appear in site: results without being the indexed URL for ranking.
• Crawl budget: Repeated redirects consume crawl time that could be used elsewhere.
• Unupdated backlinks: As long as they exist, the problem continues.

Is this statement consistent with real-world observations?

Yes, and it's actually a classic in SEO audits. Sites with years-old 301 redirects frequently show up in crawl logs. The problem is rarely the redirect itself — it works — but rather the persistence of bot traffic on outdated URLs.

What's more unclear is the exact timeframe for the canonical to switch permanently. Mueller mentions 'a few times,' but it can range from a few days to several weeks depending on the site's crawl frequency and the quality of the backlinks. [To be confirmed]: Google has never given a precise figure, and it clearly varies from site to site.

What nuances should be added to this rule?

First point: not all external links are created equal. A backlink from a high-authority site will trigger more frequent crawls than a link buried in a dying directory. If an old URL is still receiving juice from a powerful site, Googlebot will go back there regularly.

Second nuance: the behavior described by Mueller does not apply the same way to chain redirects. If A redirects to B, which redirects to C, Google may take much longer to stabilize the canonical or may never do it completely if the chain is too long.

When does this logic become problematic?

The real issue arises with mass migrations. When a site changes its domain or revamps its URL structure, thousands of 301 redirects may be implemented all at once. If a significant portion of external backlinks still points to the old domain months later, the crawl budget skyrockets.

Another problematic case: multilingual or multi-regional sites that merge versions or rearrange their hreflang. The old URLs remain crawled, but signals may scatter between multiple canonical versions if the setup is not clear. The result: dilution of authority and confusion in the index.

What should you do after a migration or redesign?

The first step is to map the backlinks pointing to the old URLs. Tools like Ahrefs, Majestic, or Semrush can help identify the strongest links. If a third-party site with good authority still points to a redirected URL, contact them to request a link update.

Next, ensure that your 301 redirects do not create chains. A chain A → B → C slows down crawling and dilutes signals. Always redirect directly to the final destination. If you inherited historical redirects, now is the time to clean them up.

How to check if the canonical has switched to the new URL?

The Google Search Console remains your best ally. In the Coverage section, check which URLs are indexed. If the old URL still appears as the canonical weeks after the redirect, that's a warning signal. Also, use the URL inspection tool to verify which version Google considers canonical.

Server logs are also valuable. Analyze the crawl frequency of old URLs: if Googlebot is still visiting them regularly months after the migration, it's because active backlinks persist. Cross-reference this data with your backlink list to identify sources to correct as a priority.

What mistakes should absolutely be avoided?

Never delete 301 redirects on the grounds that "it's been over a year." As long as an external backlink exists, the redirect should remain in place; otherwise, you generate 404s and lose the SEO juice passed along. This is a common mistake after a migration: cleaning up too early and breaking links that were still passing authority.

Another trap: believing that the site: command reflects the actual index. If you still see old URLs in a site:example.com query, it doesn’t mean they are indexed for ranking. Rely on the Search Console and logs, not site: searches, which show a broader set of URLs known to Google.

• Map the backlinks pointing to old URLs and contact third-party sites for updates.
• Check that no redirect chain exists (A → B → C) and correct it if necessary.
• Use the Search Console to confirm that the canonical has switched to the new URL.
• Analyze server logs to identify old URLs still being crawled regularly.
• Never remove a 301 redirect as long as an active backlink points to the old URL.
• Do not rely solely on the site: command to assess the indexing status.