Conversation so far:
How did this company come about?
Carnegie worked to develop several iron works, eventually forming the Keystone Bridge Works.
What had he been doing previous?
Carnegie invested $40,000 in Story Farm.
What was Story Farm?
oil wells on the property sold profitably.
How much did they make from the oil?
the farm yielded over $1,000,000 in cash dividends.
What other items were they making?
Carnegie worked with others in establishing a steel rolling mill.
What else were they producing?
Carnegie worked to develop several iron works.
What else were they doing to grow the business?
He used his connection to the two men to acquire contracts for his Keystone Bridge Company.

Question: What did he do after that?
Self-contained rewrite: What did Andrew Carnegie do after acquiring contracts for Keystone Bridge Company?