Simplify the following text for a Grade 11 native English-speaking person.
Original: The original and most famous was operated by the Delmonico family during the 19th and early 20th centuries , but the last family-owned restaurant closed due to a Prohibition-era slowdown in 1923 .
Simplified: The original and most famous was operated by the Delmonico family during the 19th and early 20th centuries , closing due to a Prohibition-era slowdown in 1923 .