Mortality Statistics 1918. Nineteenth Annual Report.

From Causes of Death, p. 27:

"Influenza and pneumonia (All forms).

"In 1918 the registration area (exclusive of Hawaii) 477,467 deaths wee assigned to influenza and pneumonia (all forms). In the latter part of that year a pandemic on influenza swept over the country and did not fully spend its force until well into 1919....

"The 477,467 deaths from influenza and penumonia (all forms) in 1918 correspond to a rate of 583.2 per 100,000 population as against 125,795 in 1917 and a rate of 167, which till 1918, was the highest rare from these causes for any year since 1910. Fully 79.8 per cent of the mortality from these causes in 1918 occurred in the last four months of the year...."

Digital facsimile from Google Books at this link.