In the 1790s, Charles's great-great-great-grandfather, Sven Olofsson, adopted the surname Wahlgren (Swedish pronunciation: [ˈvɑ̂ːlɡreːn])[citation needed] during his military service, a family fact passed down over the generations.

When Charles's father, Carl Magnus Olofsson, came to America from Sweden, he decided to change the family name to Walgreen.

While serving in Cuba, he contracted malaria and yellow fever, which continued to plague him for the rest of his life.

[6] After his discharge, Walgreen returned to Chicago and worked as a pharmacist for Isaac Blood.

Walgreens offered low-priced lunch counters, built its own ice cream factory, and introduced the malted milk shake in 1922.