The SEO of Migrating to a New Site

When building a new website, everyone gets excited and a ton of work goes into the new design, the new content architecture, what features should be included and so on, down to very minute details. The item that is often forgotten is that the legacy site has almost certainly accrued some SEO value. If no plan is put in place to migrate that value to the new site, you will most likely see a drop in search traffic following the launch of the new site.
You may have heard that you should put in place a 301 redirect plan. But what does that mean? Do you have to map all pages? What do you do if your new site does not have the same structure and all the same content as the old site?
Below is an easy to understand process for planning and executing a “Top Pages Migration” to balance harnessing the highest value content with the effort required. If you would like a more technical description, Aleyda published a great, very detailed blog and infographic on acheiving an SEO-friendly domain migration.
Evaluate SEO valuable pages on the legacy site
The first obvious question is what content is valuable enough to spend effort maintaining the SEO value. Moz’s Open Site Explorer tool is great for this. There is a top pages report that you can download and order by page authority. The tool also identifies inbound and internal links which will also be pages you want to consider.
You can also use your web analytics tool to identify pages that get a lot of traffic from organic search. By definition, these pages have SEO value.
Select pages to migrate
Depending on your site size and traffic, the targets will change but the idea is set a rough cut-off in the different factors you are looking at:
  • page authority
  • number of inbound links
  • web traffic form organic search
I say rough cut-off because this is more an art than a science. You may decide to migrate an entire section for consistency even though there are a few of the pages that fall below your chosen targets.
Map the old content to the new site in a redirect plan
Many of the pages will likely map easily one-to-one. Others will not. For the pages that do not, the generally suggested approach is to find the section of the new site that most closely matches the old content and map to the landing page of the new site section.
The redirect plan itself, can take different forms but I have found the simplest is a straightforward excel file. Below is an example.
Create the redirects
For actually redirecting the traffic request for the old page to the new page, you will want to use 301 redirects. Google gives a high-level description of 301 redirects in the Webmaster tools support. There is also a great in-depth guide to redirects available on .
If you are less technically inclined, don’t worry. If you provide the excel file described to a developer and ask them to create 301 redirects, there should be no problem. You will want the redirects in place as soon after the new site is live as possible in order to maximize the value on your new site. If you can have the old and new site running in parallel, this can reduce the chances of errors for users or search engine crawlers that are trying to access the old site. As the redirects come on-line, both users and search engine crawlers will be redirected to the pages on the new site. You don’t want to run the old site in parallel with the new site for too long, not only because you are paying for 2 sites but also because it creates somewhat duplicate content which can lead to penalties from search engines.
Test the redirects
As with any change to your site, you will want to test each of the redirects to make sure they are working as expected.
When migrating to a new site, it is almost guaranteed that you will see at least a small drop in organic search traffic. Follow the steps to minimize that drop and start your new site off strong!

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