District Help

I’m looking for some help and clarification on districting.
If I’ve got an area producing copper, sand, iron, carbon, steel, electronics, microchips, and motors, do I have to identify each producer as its own district and create an export rule for another district within the same area, or can I paint them all as a single district, and drag an export rule within that same painted area for each resource?

Each district is unrestricted as to how many different products it produces or consumes.

For each product, if a district has export rules for that product it will only ship that product to those districts. Otherwise it can ship that product anywhere it can reach.

A product can ship within a district regardless of any export rules.