Yaƙin basasa na Amurka (12 ga Afrilu, 1861 - Mayu 9, 1865; wanda kuma aka sani da wasu sunaye) ya kasance yakin basasa a Amurka tsakanin Tarayyar (jihohin da suka kasance masu biyayya ga Tarayyar Tarayya, ko "Arewa") da kuma Ƙungiya (jahohin da suka zaɓi ballewa, ko "Kudu").Babban dalilin yakin shine matsayin bauta, musamman fadada bautar da aka samu a cikin yankunan da aka samu sakamakon Sayen Louisiana da Yakin Mexico-Amurka.A jajibirin yakin basasa a shekarar 1860, miliyan hudu daga cikin Amurkawa miliyan 32 (~ 13%) sun kasance bayi ne bakar fata, kusan duka a Kudu.Yaƙin basasa na ɗaya daga cikin mafi nazari da rubuce-rubuce game da abubuwan da suka faru a tarihin Amurka.Ya kasance batun muhawarar al'adu da tarihin tarihi.Abin sha'awa na musamman shine tatsuniya na ci gaba na Bacewar Dalili na Ƙungiya.Yaƙin basasar Amurka yana cikin waɗanda suka fara amfani da yaƙin masana'antu.Titin dogo, telegraph, jiragen ruwa, jirgin ruwan yaƙi, da makaman da aka kera da yawa sun yi amfani sosai.Gaba daya yakin ya yi sanadin mutuwar sojoji 620,000 zuwa 750,000, tare da jikkata fararen hula da ba a tantance ba.Yaƙin basasa ya kasance mafi munin rikicin soji a tarihin Amurka.Fasaha da rashin tausayi na yakin basasa sun nuna alamun yakin duniya masu zuwa.