Tesla Inc.’s decision on where to build a new U.S. automobile assembly factory will be influenced by state incentives as well as access to a large workforce and low logistics costs, Chief Executive Elon Musk said.

Mr. Musk on Tuesday said on Twitter that the Silicon Valley electric-car maker is scouting locations for a new factory in the U.S. to build the company’s coming pickup truck and Model Y compact sport-utility vehicle.

“Incentives...