If a migration has one load-bearing artifact, it's the redirect map: the spreadsheet that says, for every URL on the old WordPress site, exactly where visitors and search engines should land on the new one. Done right, it's boring and nobody ever notices. Done wrong, it's the main way sites lose 20–60% of their traffic in a week. Here's the full process for redirecting old WordPress URLs after a migration — inventory, mapping, implementation, and verification.

Step 1: Inventory Every URL (Including the Weird Ones)

Pull URLs from three sources and merge them: a full site crawl, your XML sitemap, and Google Search Console's Pages report (which catches indexed URLs your crawl missed). WordPress generates far more URL shapes than its admin ever shows you:

• Posts and pages — plus the /feed/ variant WordPress appends to nearly everything
• Category, tag, author, and date archives, each with /page/2/, /page/3/ pagination
• ?p=123 and ?page_id= shortlinks that resolve to real posts
• Attachment pages — WordPress creates a standalone page per uploaded image
• wp-content/uploads/... media files that other sites hotlink or link to directly
• Old permalink structures from previous settings changes (/2019/05/slug/ style), which may still receive traffic through existing redirects

Prioritize ruthlessly: sort by traffic (Search Console) and by backlinks (any backlink tool). A URL with zero visits and zero links needs a sensible rule-based redirect at most; your top 100 pages deserve individual attention.

Step 2: Map One-to-One, Not Many-to-Homepage

Every old URL gets the single most equivalent new URL. Google's guidance on site moves with URL changes is explicit that redirects should point to matching content — bulk-redirecting everything to the homepage gets treated as a soft 404, and the ranking equity evaporates. Practical mapping rules:

• Post → the same post at its new URL (ideally keep slugs identical and this section maps itself)
• Category archive → the equivalent category or listing page
• Thin archives you chose not to rebuild (date, author) → the closest meaningful parent, usually the blog index
• Deleted content → let it 404 or return 410 deliberately; a redirect to something irrelevant is worse than an honest 'gone'
• Attachment pages → the post that contained the image, or 410 if orphaned

Keep slugs stable if you can

The cheapest redirect is the one you don't need. If the new platform can serve /my-post-slug at the same path, the entire post section needs zero per-URL work — one reason to decide URL structure before the rebuild, not after. This is step 7 in the full migration checklist.

Step 3: Implement — Rules First, Exceptions Second

Express the map as a small set of patterns plus an exception list, in this order:

1. Exact-match redirects for your individually mapped top pages
2. Pattern rules for structures: /category/(.*) → /blog/category/$1, /(\d{4})/(\d{2})/(.*) → /$3
3. Cleanup rules: strip /feed/, resolve ?p= IDs, collapse /page/1/ duplicates

Where they live depends on your stack: edge redirects at the CDN (fastest, first choice), server config, or the CMS's own redirect manager. Two hard rules regardless of where: always 301 (permanent), not 302, and never chain — if A redirected to B years ago and B now moves to C, point A directly at C. Each extra hop leaks crawl budget and latency. On the EmDash side, how to set up redirects in EmDash CMS covers the implementation specifics.

Step 4: Verify Before and After Launch

• Run the entire inventory through a crawler against staging (with hosts overridden) or immediately at launch — every row should return exactly one 301 to a 200
• Check for chains and loops — crawlers flag both
• Spot-check the top 20 URLs by hand in a browser, including a few ?p= shortlinks and /feed/ URLs
• Watch Search Console's Coverage report daily for two weeks for 404 spikes — new 404s mean inventory you missed

Step 5: Leave It Alone for a Year

Google recommends keeping migration redirects live for at least twelve months; in practice, leave them permanently if the rules are cheap to keep. Backlinks from other sites will point at old URLs for years, and every one still delivers visitors and equity — as long as the 301 is there to catch them. The redirect map isn't launch scaffolding to tear down; it's part of the new site's foundation. For everything that happens around this step, the WordPress migration checklist has the full sequence, and the SEO impact guide explains what to expect in the rankings while Google processes the move.