The electoral wards used to create the current constituency are entirely within the preserved county of Gwynedd; They are Arllechwedd, Bethel, Bontnewydd, Cadnant, Cwm-y-Glo, Deiniol, Deiniolen, Dewi, Garth, Gerlan, Glyder, Groeslon, Hendre, Hirael, Llanberis, Llanllyfni, Llanrug, Llanwnda, Marchog, Menai (Bangor), Menai (Caernarfon), Ogwen, Peblig, Penisarwaun, Pentir, Penygroes, Seiont, Talysarn, Tregarth and Mynydd Llandygai, Waunfawr and Y Felinheli.

[6] The latest boundary change created a battleground in Arfon particularly for Labour, Plaid Cymru, and the Conservatives, with the latter being labelled as a 'resurgent' party by the Caernarfon Herald.

[7] The scale of contention had been reached due to the large shift in boundary changes which in turn created a need within each party to achieve a relatively unforeseen outcome.

Plaid Cymru had previously never represented Bangor, which had been held by Conservative Wyn Roberts for twenty-seven years and a further thirteen under Labour's Betty Williams.

In the event, Plaid gained the seat (which had been notionally Labour) in 2010 and held it in 2015; their victory in 2017 was by just 92 votes, the tightest margin in Wales in that election.