I thought that and then checked the numbers.

Shipping is negligible and when compared by energy per tonne per km, can be up to almost 100x better than road, so going 200km by road can compare to going nearly 20000km by sea in some cases.

Putting everything in one place could get savings from many factors, but transport doesn't appear to be that major compared to the others.

Trains and boats carbon footprint are pretty low. It's trucks and planes that are bad...