They are young, diverse, mobile, socially aware and part of a long-sought transformation in Utah’s urban core. Twenty-somethings are driving a residential boom in the heart of Salt Lake City, with thousands of new apartments, condominiums and town homes being built to cater to the living needs of these so-called millennials. Utah’s younger demographics, its sturdy job market and a blossoming tech sector have combined with a light-rail system and premier outdoor and cultural attractions to lure a...