In the name of Allah the Beneficent the Merciful
Peace, blessings and mercy of Allah be upon you.
Praise be to Allah, prayers and peace be upon His kind Messenger, family members, companions and followers.
They are Halal and permissible to eat, though they are categorized under "doubts", which if avoided by Muslims, would be better. Laws and rules here in America stipulate that animals and birds are slaughtered the same way as in our Shari`ah. Masses of doctors of Fiqh, who are right in their judgment, interpret the meaning of Allah`s saying: "Eat not of (meats) on which God`s name hath not been pronounced", (Quran, 6:121), as do not eat what other than the name of Allah is mentioned on it, and here in America, they do not mention the name of Allah on the slaughtered animals and birds, and neither any other name, therefore, they are Halal and permissible to eat from this perspective. However, the source of doubt is that they people who work in American slaughterhouses include a great number of Buddhists from China, Korea, etc, who are not from the people of the Book. Late Sheikh Ibn Utheimeen, may Allah have mercy on him, when he was receiving medical treatment here in America, made it Halal and permissible to eat it, and he said that as long as the country is one that its majority are from the people of the Book, then their slaughtered animals and birds are Halal and permissible to eat, even if there is a small percentage of idol-worshippers among those who work in slaughterhouses. Allah knows best.