If we eat food from local sources, we can decrease our ecological footprint, reduce carbon emissions, and eat better food. In addition, any society that cannot produce its own food is vulnerable, as it cannot create one of society's main sources of wealth. It just makes sense to grow food locally.
The same principles apply to manufacturing. Grow locally, eat locally; more generally, consume locally, produce locally. In the case of manufacturing, "producing locally" would mean consuming goods that were mostly manufactured within your major metropolitan area, with most of the rest coming from around the country, but certainly not from around the world.
