In one major city, you create a major factory, e.g. a car assembly factory, and this not only gives work to thousands of people working there directly, but also cooperants, other factories, that supply this factory with small parts and services. The car assembly factory is then understood as "Carrier" or "Pulling horse" of the local economy and production. Absence of such "Pulling horse" makes economical activities hard. Example is my home city of Maribor, wher after the bancrupcy of truck making factory pulled into bancrupcy half of the other economical subjects and resulted in up to 25 % unemployment.

So "Pulling horse" must be, even if it demands constant finnacial aid (to the reasonable amount, that is).