Mean length of freeze-free period (days) /
United States.Weather Bureau.
Washington, D.C. : The Bureau,
1962.
Title at top of map and lower right margin.
Base map  by United States Weather Bureau."
"Subject data based on 2565 station records, 1921-1950."
"Standard parallels 29 1/2° and 45 1/2°."
Includes inset maps of Alaska and Hawaii, and notes to assist map interpretation.
"For sale by Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., price 10 cents per sheet."
Bartholomew firm library.
Temperature