I am working on a project where I need to find, for each US congressional district, how much of the congressional district's perimeter overlaps with a city or county boundary. Since the boundaries are unlikely to overlap exactly, I also preferably want to be able to specify a tolerance - So, for instance, boundaries might be considered overlapping as long as they're within 50 meters of each other. Is there any way to accomplish this in QGIS?
I'm using US Census TIGER data, which provides separate shapefiles for congressional districts, city boundaries, and country boundaries.
I think that firstly you should convert polygons to lines (congressional district's perimeter), make 50m buffer and nextly overlap a result with a city or county layers and at finish sum overlaped perimeters.