While this poem might seem kind of random at first glance, it's strictly structured meter-wise. For starters, the whole thing is iambic, meaning that each line is made up of a series of stressed and unstressed syllables called iambs. Though the meter shifts as we make our merry way through both five-line stanzas, each stanza follows the exact same metrical pattern.
The first two lines are in iambic dimeter, meaning that there are two iambs per line ("di-" = two), as in:
From Blank to Blank—
A Threadless Way
(1-2)
Then we switch to iambic trimeter, which means that there are three iambs per line ("tri-" = three):
I pushed Mechanic feet. (3)
After that, we go to iambic tetrameter, with four iambs ("tetra" = four):
To stop—or perish—or advance— (4)
And we end back in trimester:
Alike indifferent— (5)
Now, check out the final stanza, and you'll see that it follows the exact same pattern:
If end I gained
It ends beyond
Indefinite disclosed—
I shut my eyes—and groped as well
'Twas lighter—to be Blind— (6-10)
This choice of a strictly structured, repetitive meter makes a lot of sense for this poem because that language is describing someone who's repetitively trudging from one blank to another. The speaker is trapped in a monotonous, repeating cycle that she just can't escape.
This metrical pattern can also be seen as a variation on one that Emily used a lot: hymn, or ballad, meter. This is a style of meter popular in—you guessed it—church hymns, especially ones written by Isaac Watts, whose hymns were big hits at the church Dickinson attended when she was growing up.
Ballad meter alternates between tetrameter to trimeter (four iambs to three) with each line. This poem starts with a line of two iambs... though we could choose to see the first two dimeter lines of each stanza as being a tetrameter line that's chopped in half. After all, 2 + 2 = 4, right? (We're glad we packed our calculators.)
Look at the first stanza again to think about it that way:
From Blank to Blank—
A Threadless Way
I pushed Mechanic feet.
To stop—or perish—or advance—
Alike indifferent—
This leads us to ask: what's the big idea in chopping the tetrameter line in half? Well, it's a poem about moving from one blank space to another, right? So why not leave a gaping hole in between the metrical feet? All in all, it's poignant to use this distorted form of ballad meter in a poem that's about total depression. In some subtle way, this break might be meant to show how the speaker can't find any comfort in hymns or religion.