How to identify polygons on the boundary

Question

Hello.

I'm using arcgis pro 2.8.3. The pink part in the image attached is a geodatabase of census block groups of LA county. I want to find all the block groups that are on the boundary/border of this map. I know one option would be to eyeball which polygons lie on the border and manually select them. But I was wondering whether there are any commands/analysis tools that I may use in this case.

Thank you for your help.

find_border_polygon.png

FAFA0E81-2B50-4714-9F34-91CE7E078556.JPG

DanPatterson · Accepted Answer

Select features by location—ArcGIS Pro | Documentation

Select By Location graphic examples—ArcGIS Pro | Documentation

boundary touches  or share a line segment with