The real wordsTheory
Why the question comes up at all
Two families of reason, and the class numbers them.
1. Addition of new facilities. As part of a marketing strategy to expand markets, or because growth in demand cannot be satisfied by expanding the existing facilities.
2. Relocation. Depletion of the basic inputs, a shift in markets, or the cost of doing business at a particular location making a move attractive.
Growth pushes you to add. Depletion, market shift and cost push you to move.