In his Southern Harmony collection, William Duckworth extracts existing material from shape-note hymns found in William Walker's 1835 publication A Southern Harmony and Musical Companion. He then applies minimalist and postminimalist processes to this material to create innovation choral compositions. This document provides a comprehensive analysis of the methods used to construct all twenty works in Duckworth's collection by tracing the extracted source material through the fabric of the new compositions. This study provides substantial evidence of Duckworth's place as a pioneer of the postminimalist genre. It also provides a discussion on the vocal implications of utilizing shape-note hymns as source material as traditional performances of the genre are typically associated with a unique vocal style.