Conversation so far:
what does the united states produce the most of
The largest manufacturing industries in the United States by revenue include petroleum, steel, automobiles, aerospace, telecommunications, chemicals, electronics, food processing, consumer goods, lumber, and mining.
does the united states produce airplanes
A large portion of U.S. industrial output, the United States leads the world in airplane manufacturing.

Question: which companies manufacture the planes
Self-contained rewrite: which companies in the united states manufacture airplanes