As of December 1st, 2025. Garmin requires you to check the “Historical Data“ box during sign in. If you do not enable this toggle, your historical activities will not be accessible.
I’m updating this page on the day of the unannounced change, so there’s still a lot for me to learn. If you logged in and did not enable this toggle, I suggest logging out of CityStrides & logging back in with that toggle enabled. You can then post in the missing activities thread if you need your older activities synced. 
yay.
As of August 1st, 2021. Garmin only allows access to 5 years of historic data. This is a rolling limit, so the 5 years goes back from whatever “today” is when you connect Garmin to CityStrides.
Any activities already synchronized into CityStrides will remain here, unless you delete them.
There may be workarounds along the lines of:
- Export your data from Garmin
- You will probably need to use the Export Your Data feature in their Data Management page
- Import the data into a service that does not have this data access limitation
- Connect that service to your CityStrides account within your Settings page
- Pause that service after the old activities have arrived in CityStrides
If you are able to find a workaround for this issue, know that the syncing system will skip activities with the exact same start time. This will allow you to connect another service which may have some overlapping activities & not produce duplicates in CityStrides.