Why doesn't the Episcopal Church (USA) use the title ‘Archbishop’?

Most Churches in the Anglican Communion make use of the title of 'Archbishop', particularly for heads of provinces or Churches within the Communion. However, the Episcopal Church in the USA (despite having 'episcopal' as its name) does not make use of the title of Archbishop , reserving just the title 'Primate' for its head. Is there a theological reason for this? The title of 'Archbishop' is ancient and has no more political connotations than the title of 'bishop', so I don't see why the Episcopal Church would avoid it.