Showing, while millions of souls hurry on,
The virtues of collars, from sunset till dawn,
By dart or by tumble of whirl within whirl,
Starting new fads for the shame-weary girl,
By maggotry motions in sickening line
Proclaiming a hat or a soup or a wine,
While there far above the steep cliffs of the street
The stars sing a message elusive and sweet.
Now man cannot rest in his pleasure and toil
His clumsy contraptions of coil upon coil
Till the thing he invents, in its use and its range,
Leads on to the marvelous CHANGE BEYOND CHANGE
Some day this old Broadway shall climb to the skies,
As a ribbon of cloud on a soul-wind shall rise.
And we shall be lifted, rejoicing by night,
Till we join with the planets who choir their delight.
The signs in the street and the signs in the skies
Shall make me a Zodiac, guiding and wise,
And Broadway make one with that marvelous stair
That is climbed by the rainbow-clad spirits of prayer.
This is the point where the poem turns surrealistic and fantastical. Lindsay muses how that man’s constant quest for preoccupation through work, or his constant need to have and make things for entertainment, may eventually lead to “this old broadway” (I’m assuming he’s personifying the neon sign from the first stanza) reaching the skies and joining the stars from the second stanza’s first line. 
 (There’s inversion in the “choir the delight” of line 20) 
 At this point he is employing extremely vivid imagery to describe how neon signs shall reach the heavens and the cosmos, and become a sort of “stairway to heaven” where he, and the rest of humankind, shall climb up, clad in the effervescent colors of the neon signs he initially so deplored. Whether such a fantastic tone for a poem that started off as biting social commentary is Lindsay being facetious or sarcastic, or simply a delightful daydream, is up for the debate.
A Rhyme About an Electrical Advertising Sign