United States includes the States, the District of Columbia, the Commonwealth of Puerto Rico, the Commonwealth of the Northern Mariana Islands, Guam, the Virgin Islands, American Samoa, and Native American governments. III Development and Deployment of a Mortgage Security Market Exchange, Data Repository, and Covered Bond Market 301. Purposes The purposes of the national mortgage security market exchange created by this title are— (1) to enhance efficiency, liquidity, and security in the secondary market for residential mortgages, including mortgage-backed securities