“Do you care about 20th-century American poetry? If so, you may be embarrassed to admit it. In our culture, too many regard poetry, and especially the poetry of the last century, as having all the real-world utility of underwater basket-weaving. That reputation, though unfortunate, may be well deserved. A quick glance at Ezra Pound’s sprawling, self-indulgent, showily allusive Cantos will reinforce this impression. Another glance at his political screeds may solidify it. Pound isn’t all of it, of course — and that raises another issue. What does one mean by 20th-century American poetry? Where does one start? Robert Frost’s rugged philosophizing or Wallace Stevens’s imaginative dreamscapes? And what binds Claude McKay’s socialist realist sonnets to the L=A=N=G=U=A=G=E poets’ scientistic abstractions? Can we really expect to sort through so many different voices from so many different backgrounds? In fact, there are many points of entry. And one of the most…