This book examines the influences on the American music of the 20th century from a musicological rather than a sociological perspective. But actually there is a fair bit of historical and cultural background included as well. For me this was a good thing, because I am a music fan rather than a musician and sometimes found all the talk of pendular thirds, eight bar patterns and the diatonic scale going over my head. But even here I found enough discernible to hold my interest.
The primary emphasis is on how African musical forms and European musical forms, especially those of the British Isles, interacted in the American South to create blues, jazz, country, ragtime, bluegrass and many other significant musical genres. The author finds some suprising similarities between traditional African music and the folk music of Europe in both instrumentation and style. He says this makes sense because both continent's music had been previously influenced by "The Old High Culture" music which had first developed in ancient civilizations, such as Egypt and Mesopotamia, and later been brought over to both Africa and Europe by Arab Muslims. This argument might at first seem a bit far fetched. But Van Der Merwe does make a very good case for it.
The latter part of the book focuses almost exclusively on musicological topics, not all of which were entirely comprehensible to me. But I did enjoy the examples of some classic blues and folk lyrics that were included along with the musical notation. So even for a non-musician like me there was still plenty to appreciate here.