How to Set Up Cross-domain Tracking in GA4 (And Comparison Notes to UA)

If you want to use Google Analytics 4 to track a visitor as a continuous session on two or more related sites you need cross-domain tracking.
Cross-domain tracking in GA4 is far easier than it was in Universal Analytics.
Google's support article on cross-domain tracking in GA4: support.google.com/analytics/...
Have questions or comments? Leave them in the comments. I'm always up for learning more...and for new video ideas.
There's typically a new video every week or two about GA4 or Google Tag Manager or Looker Studio or sometimes Google Ads or SEO. If you want to follow along with what I'm learning (trying to learn) you can subscribe at the link below:
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✭ Do These 10 Steps to Install AND Configure GA4 Properly: www.rootandbranchgroup.com/ga...
✭ Events in GA4 and How it Compares to UA: www.rootandbranchgroup.com/ev...
✭ GA4 Reports Explained: Standard Reports, Explorations, Custom Reports: www.rootandbranchgroup.com/ga...
✭ Google Analytics 4 vs. Universal Analytics: www.rootandbranchgroup.com/go...
✭ A Practical Guide to Event Parameters: www.rootandbranchgroup.com/ga...
✭ GA4 Problems (And What You Can Do About Them): www.rootandbranchgroup.com/ga...
✭ Google Analytics 4 Link Click Tracking: www.rootandbranchgroup.com/go...
✭How to Install Google Tag Manager (GTM) on Wordpress: www.rootandbranchgroup.com/ho...
✭And Some SEO! How to Edit robots.txt on Wordpress!
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🔗 Links to 📹📹📹 VIDEO TUTORIALS: These are most popular GA4 instructional videos as measured by views or watch time
📺 How to Set Up GA4 in 5 Minutes With GTM: • Set Up GA4 (in 5 Minut...
📺 How to Properly Configure Your GA4 Property: • 10 Steps to Configure ...
📺 6 Key Differences Between GA4 and UA: • Google Analytics 4 (GA... 🔑🔑🔑🔑🔑🔑
📺 The Truth About GA4 Event Parameters: • The Truth About GA4 Ev...
📺 GA4 Hits, Events, Sessions, and Users Explained: • Google Analytics Event...
📺 How to set up GA4 FORM SUBMISSION tracking with a thank you page: • How to Set Up a GA4 Fo... 🙏
📺 How to set up BUTTON CLICK tracking with GA4 and Google Tag Manager: • Set Up Page Timer Trac...
📺 How to set up PAGE TIMER tracking with GA4 and Google Tag Manager: • Set Up Page Timer Trac... ⏲
📺 How to Set Up LINK CLICK Tracking with GA4 and Google Tag Manager: • Button Click Tracking ... 🖯
📺 How to Set Up SCROLL DEPTH Tracking (25%, 50%, 75%, 90%) with GA4 and Google Tag Manager: • How to Set Up GA4 Link... 🖯
📺 How to Build a Link Click Tracking Report Using GA4 data and Looker Studio: • Google Data Studio GA4... 📊📊📊
📺 Campaign Tracking in GA4 to See UTM Tagged Traffic: • Campaign Tracking GA4 ...
📺 GA4 Conversion Tracking Compared to UA: • GA4 Conversion Trackin...
📺 Registering Custom Dimensions in GA4 Explained: • GA4 Custom Dimensions ... -
📺 How to Link GA4 and BigQuery: • Google Analytics 4 + B...
📺 Users in GA4 Explained vs. UA Users: • GA4 Users Explained: N...
📺 Creating and Using Audiences in GA4: • How to Create GA4 Audi...
📺 3 Practical Ways to Use the Path Exploration Report: • GA4 Path Exploration: ...
📺 How to Set Up Site Search in GA4 and UA: • Video
📺 Video review of the Source/ Medium report in GA4: • GA4 Reports: How to Re...
📺 All about the GA4 Certification: • Google Analytics 4 Cer... 🏆
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Thanks for coming by!

[@Bedazzle_Harder]

Thanks a ton! This really simplified the process! I was about to go add code to every page on my subdomain. You're a lifesaver!

[@rooted-digital]

So glad to hear it! GA4 makes enough stuff complicated, so it’s nice to have the subdomain tracking be one of the simple ones

[@AlignDigital]

Hey Zack, whereas other guys spent mins and mins going around GA4... you just go straight to the key questions. Love your videos mate!

[@rooted-digital]

I wonder if the difference is because some of those other guys know a lot more than me. I'm trying to focus my limited brain cells on what they can handle. Ha! But I really do appreciate it, Jim. Thanks for the kind words!

[@romnaviche]

Thank you for posting!

[@rooted-digital]

You are quite welcome. Glad you found it useful Gabriel!

[@KrishnoRoy360]

Very Helpful video for me

[@rooted-digital]

So glad to hear it. Thanks for the feedback! 🙂

[@kathrynlaing5535]

thank you!!

[@rooted-digital]

You are quite welcome, Kathryn. I appreciate it. 😄

[@pubududissanayaka1447]

Thank you

[@rooted-digital]

Quite welcome! Best wishes to you in all things GA4.

[@tomogilvie5913]

Hey Zack, great video and sorry if this seems like an obvious question but I'm gonna ask it anyway :) As I understand it, for cross domain tracking to work, website A & website B have to use the same GA4 measurement ID, is that correct? If so, if a GA4 property is already set up, implemented and working on website A, would it then just be a simple case of taking the GA4 tag code & adding that to website B, is that correct? That would mean you wouldn't need to set up a 2nd GA4 property for website B, you'd just be using the same GA4 property for both sites, is that right? That's the bit I was struggling to get my head around. Thanks!

[@rooted-digital]

Yes, that's right. One GA4 property (with the Measurement ID deployed on both domains). Thanks for asking the clarifying question. I don't think I made that clear in the video. If you think of it, you can check back here and let me know that it's (hopefully!) working for you as expected. Best wishes!

[@johnniefp]

Thanks for the clear video. For those of us using Tag Manager do you know if you can use GTM-TKXXXXCH instead of the GA4 Measurement ID?

[@rooted-digital]

Hi John. Glad it was useful for you. Even if you are using GTM to deploy your GA4 tag (that’s how I’m doing it as well), you’ll still need to use the GA4 measurement ID. If I’m understanding your question correctly, let me know if I can help you locate it. Cheers! Zack

[@mondistributeur326]

@@rooted-digital thank you for this video. Its mean we have tu put GTM tag + GA4 tag in our code ?

[@rooted-digital]

@@mondistributeur326 Hi there. Do you already have GA4 set up on your web site? If so, you don't need to make any other changes to your site code...all the work to be done is in GA4 as outlined in the video. If you haven't yet set up GA4, you need to do that first. Personally, I think it's easiest to deploy GA4 using Google Tag Manager. Here's a video showing how to do that in about 5 minutes if you are looking for that info: kzbin.info/www/bejne/sHbLqIGVbJuGnK8 Best of luck! Zack

[@bhaveshyadav8456]

How to use same GA4 property in 2 different websites ? I am stucked in cross domain tracking, please help!

[@rooted-digital]

Hi Bhavesh. Did you watch the video? If the video didn't help, I'm not sure I can add much additional help. Perhaps one key reminder is that you'll need to have the same GA4 measurement ID deployed on both domains, in addition to doing the tag configuration shown in the video.

[@shmuelherschberg3869]

This is awesome. Will it work in conjunction with Google Ads?

[@rooted-digital]

Hello, Shmuel. I believe it should work just fine as long as you have synced GA4 and Google Ads. Do you have 1 Google Ads account or two accounts for 2 domains?

[@chrislambert3708]

In my property my own domain was already listed there under the domain allow list, are you sure you don't need to have your main domain there as well?

[@rooted-digital]

You're referring to the list you access under 'Settings' --> 'Configure your domains', right? If so, you don't need your own domain there. I don't have anything at all entered there for my GA4 property set up for Root and Branch. I don't think there's any downside with having it there, so you could always just leave it if you like it there.

[@hardboxmarketing7255]

Hey Zack - great video. I'm having a little bit of an issue with this. On Site A, I have the GA4 tag connected via Google Tag Manager. However, on Site B, the GA4 tag is connected directly (i.e., without GTM) as it's a 3rd party booking software and they only support GA4. Both have the same Measurement ID and both are tracking fine, however there seems to be a disconnect with the cross domain tracking, which means that booked appointments aren't being properly attributed to the original source (e.g., paid ads). The current way things are set up is: Ad --> Site A (primary domain) --> Site B (booking website). All booked appointments are popping up as referral (i.e., referral from Site A), with no mention of where the clicks to site A originally came from. This tells me that I haven't properly set up cross domain tracking, but I can't work out what the issue is, as I've followed all the steps in your video and have even chatted to Google's support team about it (they don't know what the issue is). So, I was wondering if you have any idea what the issue could be? Should I connect GA4 to Site A directly, rather than through GTM?

[@rooted-digital]

Hello there. I'm not sure, but I think this resource I've linked below about transferring UTM parameters might be useful for you. www.analyticsmania.com/post/transfer-utm-parameters-google-tag-manager/ The hypothetical situation in the article seems fairly similar to your situation. Best wishes!

[@Pk57575]

I'm in the same situation. Did it work?

[@digitalh7202]

Zach. What happens if the second site already has an original GA4 tracking measurment ID they added originally. Can we add our measurement ID on top of that in order to track cross domain tracking?

[@rooted-digital]

I'm not sure I'm following what you mean by "add your measurement ID on top of that". The thing with cross domain tracking - that's not necessarily intuitive - is that you need to install the same GA4 Measurement on both domains that you want to track. In other words, it's a single web data stream in a single GA4 property and it's installed on both domains. Does that help?

[@digitalh7202]

@@rooted-digital Let me frame it this way: I am trying to set up cross domain tracking between Site A and Site B Site A is an ads landing page. Site B is where the conversion will take place. I know that in order for cross domain tracking to work site A and B need to share a measurement ID. What happens if Site B already had an exising measurement ID. Can I add Site A's measurement ID on top of that to make cross domain tracking work or is this impossible?

[@rooted-digital]

I see, you want to install the GA4 measurement ID for site A (landing page) on to site B so that site B will have two GA4 measurement IDs. Yes, that is what I would try. Candidly, I’m not not entirely sure what Google says about this (having multiple measurement IDs installed on a single site), but it seems like the best option assuming you want to keep your existing GA4 measurement ID / property for site B. If you would, I’d be grateful if you’d check back here with the result. I would love to learn and I will keep my fingers crossed for you. Good luck and Godspeed!

[@joaoferreiradematos9260]

Shouldn't you put also the main domain in the configuration setup?

[@rooted-digital]

Good point. I think two things: (1) It will still work as demonstrated in the video (2) What you recommend is better / safer and you should also list the main domain in the configuration setup Thanks for pointing it out.

[@maryyykayyy]

Hi Zack - I have my two different websites in the same ga4 property but they have different measurement ids. I'm confused - would I add another data stream with the 2nd website? I've Googled and everyone keeps saying to have both sites with the same measurement id but can't find anything on what that means. Sorry if this is a dumb question!

[@rooted-digital]

Hi Bethany, Is it important to track your visitors from one website to another in the same session? For some websites it is, especially if they always work together. For some websites it isn't, and in those cases it's better (I think) to not have cross domain tracking. I'm sure you've thought of this, but wanted to ask. I think the confusing part of what you've read might come down to "measurement ID" and "data stream." Those terms are essentially synonyms here. There is a unique measurement ID for each data stream. I don't think I'd create a new data stream right now. Instead, I'd consider whether I need the cross domain tracking. If you decide it's a "yes", I think you'd likely need to get rid of one of your existing properties / data streams, so you can then redeploy the same GA4 measurement tag (the measurement ID) on both domains. It is a confusing situation and I'm not completely certain, but I hope this helps at least a bit. Good luck!

[@maryyykayyy]

@@rooted-digital This is helpful - thank you so much!

[@mattiasesta7459]

Hi guys! Sorry this is not clear to me. How do I set up a GA4 account with 2 websites having the same measurement ID? Because when I add my second website to GA4 it automatically creates a new GA measurement ID, which is different from the one of the first website. I searched everywhere on the internet as well to understand how to set it up but can't find an answer. Can one of you guys help me?

[@rooted-digital]

@@mattiasesta7459 Hello there and thanks for the question. You are right that this is a confusing subject. Are you creating both of your data streams (for the 2 websites) in a single GA4 property? If so, this should work for you. You are totally right that this will create a second data stream (with a separate measurement ID) for the second site compared to the first. You'll have two web data streams with two measurement IDs in the same property. Let me know if that makes sense and it works for you. You might also consider this blog from a guy who really knows a ton about GA4: www.analyticsmania.com/post/cross-domain-tracking-in-google-analytics-4/ Best of luck!

[@mattiasesta7459]

@@rooted-digital hi! Thank you for your answer! Yes, I created both data streams on the same property (and so they have 2 different measurement ID), so is it still fine? Can I follow the process in your video and it will still work? Thanks!

[@g3nson]

Thanks! And how to disable cross-domain tracking?? I deleted all the records in there, but it still append "_ga" to URL... please help!

[@rooted-digital]

You know, I’ve never tried this myself and didn’t see anything satisfactory when I just did a little research. I’d hope that that it would resolve within 24 - 48 hrs of you removing the additional domain from your settings. But honestly I’m not sure since I can’t speak from experience. Sorry I can’t help more. Best wishes.

[@batoroaji4205]

I can't find the "more tagging settings" and seems like my interface is a bit different from this one

[@rooted-digital]

Yes, the GA4 interface has changed. Thanks for the thoughtful question. Try going into your Admin area and then click into your Data Stream. In your web stream details, click "Configure tag settings" and then "Show all" next to Settings.

[@feddu]

what if I dont want to have the _gl and _ga on the url but still use cross domain tracking ?

[@rooted-digital]

Hi there. Are you saying you've set up cross domain tracking and it's collecting data properly, but you don't see the _gl in the URL when you test it? I was reading this Google Developer's article and it seems that this _gl URL parameter is always present. developers.google.com/tag-platform/devguides/cross-domain So that means that either your cross domain tracking is not configured properly or the Google documentation is off. Keep me posted if you think the data is tracking correctly. Best wishes.

[@JuanAlbertoSanchoMelchor]

​@@rooted-digital I need to disable parameters instead. No one cross domain is configured in GA4 but url's are always shown with them. Any suggestion? Thanks!

[@phillipwoolgar7955]

The measurement ID won't match, so how do we change one?

[@rooted-digital]

Hi Phillip. If you want to track both domains in the same GA4 property, you would install the same measurement ID on both domains.

[@user-fr3gz9qq1u]

@rooted-digital I have two distinct measurement IDs: one for website A and another for website B. Is it ok to implement the website A measurement ID on website B, while keeping the website B measurement ID? Furthermore, will website B be able to access my Google Analytics insights? It's important to note that website B is one of my partner websites and not owned by me. Also, how to segment the reports/views in Google Analytics to ensure that the insights are not commingled?

[@rooted-digital]

Hi there. If I understand correctly, you have two websites, website A and website B. You'd like to do a couple things: - Track website B in its own GA4 property - Track website A and B in a combined GA4 property If you keep the website B measurement ID in its own property and also add the same measurement ID from website A to website B, I believe you can accomplish what you'd like to do (assuming I understood correctly). I haven't done this myself, but I found this blog from another site which might be worth a read: www.optimizesmart.com/using-multiple-trackers-for-cross-domain-tracking-in-universal-analytics/ In terms of segmenting the reports in GA4, you can use a hostname filter in your property that has both website A and website B. This would allow you to create reports specific to website A, specific to website B, and also have reports that show both domains together if you'd like to do that. Check out the section "How Do I See My Different Subdomains in GA4 Reports?" in this blog here: www.rootandbranchgroup.com/ga4-subdomain-tracking/ In terms of your question about website B accessing insights, I don't really understand. If you want to try and explain with a specific example, I'll see if I can add any perspective.