The publisher of a 9th-grade geography textbook has apologized for suggesting African people wilfully emigrated to America.

It comes after a mother in Texas read her son's homework and took to YouTube slamming McGraw-Hill Education for its use of language.

In a section titled 'patterns of immigration', the book describes slaves as 'workers' who came to the United States between 1500 and 1800 to work on agricultural plantations.