Final answer:
William Holmes McGuffey created the McGuffey Readers, a series of textbooks that were widely used in schools across the country.
Step-by-step explanation:
The Pennsylvania teacher who created a series of textbooks that became the basis of reading in hundreds of schools was William Holmes McGuffey. McGuffey's series of reading textbooks, known as the McGuffey Readers, were widely used in schools throughout the 19th century and early 20th century. The textbooks covered a wide range of subjects, including reading, spelling, grammar, and morality.
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