A more thorough explanation:

The Chace Act is a law that was passed in 1891 in the United States. It was created to protect the copyright of citizens from other countries who gave similar protection to U.S. citizens. This law was mainly used with European countries and was enforced by presidential order or treaty.

Under the Chace Act, books and other printed materials in English had to be produced in the U.S. or Canada to qualify for domestic protection. This means that if a book was written in English by a citizen of another country, it had to be printed in the U.S. or Canada to be protected by copyright law in the U.S.

For example, if a British author wrote a book in English and wanted it to be protected by U.S. copyright law, they would have to have it printed in the U.S. or Canada. This ensured that U.S. citizens were not losing out on copyright protection while also protecting the rights of citizens from other countries.