Relief shown by shading and spot heights.; "Based on records of about 1600 stations for the 20-year period 1895-1914, and 2000 additional records, from 5 to 19 years in length, uniformly adjusted to the same period."; Includes scale of shades, notes, chart: Period within which 50% of the annual precipitation occurs, and ancillary map: Percentage of annual precipitation occurring between Apr. 1 and Sept. 30. 40 x 60 Centimeters Scale 1:8,000,000 General Map Collection