American and overseas companies have committed nearly half a trillion dollars to build new factories for electric vehicles, semiconductors and other products in the U.S. Investors are planning to acquire or build warehouses, hotels, office buildings and apartments near coming factories across the Sunbelt and Rust Belt, where most of these so-called onshoring projects are under way, wagering that as new manufacturing hubs come online and create jobs they will produce a “multiplier effect,” with growing employment increasing demand for homes, shopping and more.