Guitar Tutorial: Casimir Pulaski Day - Sufjan Stevens
Titaniumdrew’s tutorial:
The chords are:
D - D4 | C | Am | G
At the C chord the hammer-on is on the 2nd fret on the D-string.
Then you transition to the Am chord by fingering the 2nd fret on the A string and then fingering the root of Am, which is of course the open A string itself. In Am you do the same hammer-on as you did in C.
And finally in G you hammer-on the second fret on A, before releasing it and fingering the open A string as a transition back to D.