Apple Shift Turns India Into World’s Top Maker of US Smartphones

India has overtaken China to become the top source of smartphones sold in the US, after Apple Inc. shifted to assemble more of its iPhones in the South Asian country.

In the quarter through June, India was the largest manufacturer of smartphones shipped to the US for the first time, accounting for 44% of the market, according to Canalys data. Vietnam, home to much of Samsung Electronics Co.’s production, came in second. China fell from having more than 60% of all estimated shipments a year ago to just 25%.

The stark change comes as Apple ramped up its ...