16th street is more important from up U street. South of U street, 14th street is just as important, even slightly more because 14th street has more capacity and worse traffic. It is a bustling commercial hub while 16th street has a busway, which reduces capacity and traffic, as well as less commercial space other than some hotels and shops. so yes, 16th street is more important, but 14th is just as important down U street.