The word "singing" is repeated quite often in the poem as Whitman discusses various people—workers in different occupations and activities—as he celebrates all individuals and types of work they do to be constructive and keep the country running smoothly. Each mechanic is "singing his" carol, and the carpenter is "singing his" song as he works, and the mason is "singing his" song, too. The men who work on boats are "singing what belongs" to them, and the shoemaker is "singing as he sits on his bench" while the hatter is "singing as he stands." The wood-cutter and the ploughboy sing "in the morning, or at noon intermission or at sundown." Mothers and young wives and girls are all "singing" as they do their work. Each man and woman and child is "singing what belongs to him or her and to none else," and Whitman celebrates the diversity and variety of peoples in these United States, all who contribute in their own unique ways with their own unique talents.

Part of what makes Whitman's poem so powerful is its repetition of what it means to be American.  When he opens with its title of hearing America singing, this becomes the familiar verse which is repeated in different and varied forms.  He "hears" different expressions of what it means to be America, contributing to both its vitality and the sensitivity of the poet to understand what the essence of "America" is.  The notion of varied carols is expressed in different forms and this helps to feed Whitman's conception of America, rooted in expression of "difference."  At the same time, the structure and language is extremely straightforward, helping to enhance Whitman's purpose and direction which is not aimed towards the elitist members of the social order, but rather at "typical" Americans who help to form the very basis of American identity.