This is not a rumor. It’s a press release from TSMC itself.
TSMC today announced its intention to build and operate an advanced semiconductor fab in the United States with the mutual understanding and commitment to support from the U.S. federal government and the State of Arizona.
As a reminder, TSMC is a chip fabricator with a long relationship with Apple, starting with the the A5 SoC back in 2011, and is said to be the chip fabricator behind the rumored ARM-based Mac (that last bit is a rumor).
Construction is planned to start in 2021 with production targeted to begin in 2024.
Can’t help but think about the fabled Foxconn plant in Wisconsin.