Guam er delt inn i 19 kommuner: Agana Heights, Agat, Asan‑Maina, Barrigada, Chalan‑Pago‑Ordot, Dededo, Hagåtña, Inarajan, Mangilao, Merizo, Mongmong‑Toto‑Maite, Piti, Santa Rita, Sinajana, Talofofo, Tamuning, Umatac, Yigo og Yona.