Final answer:
The religious denomination with more than 16 million members is the Church of Jesus Christ of Latter-day Saints (Mormon).
Step-by-step explanation:
The religious denomination with more than 16 million members is the Church of Jesus Christ of Latter-day Saints (Mormon). They claim about 6 million members in the US, with most of them living in Utah. Although not considered Protestants, Mormons are a significant Christian denomination.