The shoe factory in Centerville is the town' s largest firm, and it employs more unskilled workers on a full-time basis than all of the other businesses in town combined. Ttherefore, if the shoe factory closes down and ceases all operations, more than half of Centerville' s residents who are unskilled workers with full-time jobs in Centerville will lose their jobs.
The conclusion above logically follows from the premises if the assumption that the shoe factory in Centerville employs no one who is not a resident of Centerville is made.