Final answer:
The main countries that settled in the Americas are from Europe, with Spain being the first to establish colonies and initiate Atlantic exploration.
Step-by-step explanation:
The main countries that settled in the Americas originate from the continent of Europe. During the colonial era, European powers such as Spain, Portugal, and England were the first to establish colonies in the New World. Spain was the first country to establish colonies in the Americas and initiated the era of Atlantic exploration. European countries were also actively involved in the Trans-Atlantic slave trade, with West Africa being the most directly involved region in Africa.