LBJ speechwriter Richard Goodwin, in his memoir, Remembering America, noted the "president's passing passion" for alliteration. Get it? Alliteration—repeating the same letter or sound in close proximity—emphasizes a phrase or an idea, making it more memorable for many.

Your imagination, your initiative, and your indignation will determine (…) (12).

(…) the meaning of our lives matches the marvelous products of our labor (24).

There is the decay of the centers and the despoiling of the suburbs (31).

Expansion is eroding (…) (34)

They require us to create new concepts of cooperation, a creative federalism, between the National Capital and the leaders of local communities (79).

The repetition and alliteration give the speech a preacher-like quality, which seems like the tone that Johnson's going for: uplifting, inspirational, and almost hypnotic.