Or rather – He passed us –
A transition from an active to a passive role:
Here the story climaxes as the speaker realizes that instead of them passing the sun, it is the Sun who has passed them. The speaker was once active and in control, but time has caught up and taken over.
She is no longer part of this world, she is sitting with, and is thus within the domain of, death. The earth is a place for the living, and moves along for the influence of the living. The speaker does not pass the sun, as that would imply that she is moving with the orbiting earth.
To help improve the meaning of these lyrics, visit "Because I could not stop for Death (712)" by Emily Dickinson and leave a comment on the lyrics box