Air pollution. The Public Health Service first established an air sampling network in 1953. The Federal Air Pollution Research and Technical Assistance Act (PL 159, 84th Congress), under the provisions of which the present National Air Sampling Network was created, became effective in 1955. The Network's objectives are to determine the extent and nature of air pollution, to study trends in levels of atmospheric contaminants, and to investigate relationships between air pollution and socioeconomic, geographic, topographic, and other factors. Currently there are 250 sampling stations in the Network, 215 urban and 35 nonurban. The Radiation Surveillance Network is a cooperative air sampling program consisting of 74 collection stations. It was established by the Public Health Service and is operated by the Division of Radiological Health in conjunction with State health departments. Climate. The Environmental Science Services Administration, through the Weather Bureau and the Environmental Data Service, is responsible for collecting, processing, and publishing data on climate. It maintains about 11,000 weather stations, of which nearly 3,000 produce autographic precipitation records, about 600 take automatic or hourly readings of a series of weather elements, and the remainder record one observation a day. There are few records in existence for stations before 1871 although some detailed records began in the 18th century. Nearly all weather stations have been moved several times in their history. Consequently, the Weather Bureau uses "normal" values of temperature and precipitation for comparative purposes rather than long-term means which are derived from records taken at the different locations the stations may have had over the years. Normal values of temperature and precipitation are based on records for the 30-year period 1931 to 1960. For stations having records for the entire 30 years from the same instrument site, monthly precipitation and temperature normals are the means of the monthly values for the 30 years; for temperature, the normal maximum and normal minimum values were used to obtain monthly normals. The annual normal temperature is obtained by dividing by 2 the sum of the annual normal maximum value and the annual normal minimum value of temperature. For stations that did not have continuous records from the same instrument site for the entire 30 years, 1931 to 1960, the means have been adjusted to the record at the present site. In these adjustments, a "difference factor" was used for temperature and a "ratio factor" for precipitation. These factors were determined by parallel comparison, either between records at the actual station sites or through a second station that had a continuous record to compare against both sites for obtaining the resultant adjustment factors. Normals were thereafter obtained as outlined above. This system of normals has three characteristics: (1) The 30-year period (1931 to 1960) adopted for the computations is consistent with the term of years accepted by the World Meteorological Organization for climatic normals; (2) where the station and exposure for records in a given locality have been changed, the whole record has been carefully studied and adjusted to the latest source of records and reports; (3) the normals for maximum and minimum temperatures are separately tabulated. The degree-day normals are derived from the values for the monthly normal maximum and minimum temperatures, and computed from the standard base 65° F. The degree day has been defined as follows: “A unit, based upon temperature difference and time, used in estimating fuel consumption and specifying nominal heating load in winter. For any one day, when the mean temperature is less than 65° F., there exist as many degree days as there are Fahrenheit degrees difference in the temperature between the average temperature for the day and 65° F." Historical statistics.-Tabular headnotes provide cross-references, where applicable, to Historical Statistics of the United States, Colonial Times to 1957. See preface. No. 250. TERRITORIAL EXPANSION OF THE UNITED STATES AND ACQUISITIONS OF [Boundaries of all territories listed under "United States" were indefinite, at least in part, at time of acquisition. Area figures shown here represent precise determinations of specific territories which have been marked upon maps, based upon interpretations of the several treaties of cession, which are necessarily debatable. These determinations were made by a committee consisting of representatives of various governmental agencies in 1912. Subsequently these figures were adjusted to bring them into agreement with remeasurements made in 1960. See also Historical Statistics, Colonial Times to 1957, series J 1-2] 1 Includes that part of drainage basin of Red River of the North, south of 49th parallel, sometimes considered part of Louisiana Purchase. Not included in total. Ceded by Spain in 1898, the Philippines constituted a territorial possession of the United States from 1898 to 1946. Granted independence as of July 4, 1946, they then became the Republic of the Philippines. 3 Ceded by Spain in 1898 and became Commonwealth of Puerto Rico by Act of Congress on July 25, 1952. See table 5. 4 Acquired 1898; ratified 1899. Acquired 1899; ratified 1900. Under jurisdiction of United States in accordance with treaty of Nov. 18, 1903, with Republic of Panama. ? Leased (1914) from Republic of Nicaragua for 99 years. Under trusteeship. See table 5, footnote 15. Comprises following islands with gross areas as indicated: Midway (2), Wake (3), Palmyra (4), Canton and Enderbury (combined area, 27), Swan (1), Navassa (2), Baker, Howland, and Jarvis (combined area, 3), Johnston and Sand (combined area, less than 0.5), Kingman Reef, Quita Sueño Bank, Roncador Cay, and Serrano Bank (each less than 0.5), and other islands specified in table 5, footnote 8, for which area figures are not available. Source: Dept. of Commerce, Bureau of the Census; unpublished data. Represents zero. Figures are lengths of general outline of seacoast. Measurements were made with a unit measure of 30 minutes of latitude on charts as near the scale of 1: 1,200,000 as possible. Coastline of sounds and bays is included to a point where they narrow to width of unit measure, and includes the distance across at such point. * Figures obtained in 1939-1940 with a recording instrument on the largest-scale charts and maps then available. Shoreline of outer coast, offshore islands, sounds, bays, rivers, and creeks is included to the head of tidewater or to a point where tidal waters narrow to a width of 100 feet. Source Dept. of Commerce, Environmental Science Services Administration; Coastline of the United States, April 1, 1961. X Not applicable. American Samoa.. Canal Zone". Guam Trust Terr. of Pacific Is.. Virgin Islands of U.S. Represents zero. Sacramento. Juneau. San Juan 1 Dry land and land temporarily or partially covered by water, as marshland, swamps, etc.; canals under oneeighth statute mile wide; and lakes, reservoirs, and ponds under 40 acres of area. 2 Permanent inland water surface, such as lakes, reservoirs, and ponds having 40 acres or more of area; streams, sloughs, estuaries, and canals one-eighth of a statute mile or more in width; deeply indented embayments and sounds, and other coastal waters behind or sheltered by headlands or islands separated by less than 1 nautical mile of water; and islands having less than 40 acres of area. Excludes areas of oceans, bays, sounds, etc., lying within U.S. jurisdiction but not defined as inland water. 3 Year of ratification of Constitution; one of the original 13 States. See table 5, footnote 12. See table 5, footnote 15. Source: Dept. of Commerce, Bureau of the Census; U.S. Census of Population: 1960, Vol. 1, Area Measurement Reports, Series GE-20. This Series, available for 32 States as of April 18, 1967, contains revised data; subsequent adjustments will be made in cases where the land and water figures do not add to the State totals shown. 1850 158, 693 3 156, 537 1,529 772 2,156 1959 586,400 1 571,065 15,335 1959 No. 253. EXTREME POINTS OF THE UNITED STATES [The geographic center of an area may be defined as the center of gravity of the surface, or that point on which the surface of the area would balance if it were a plane of uniform thickness. Because there is no generally accepted definition of geographic center, and no completely satisfactory method of determining it, there may be as many geographic centers of a State or country as there are definitions of the term. Because many factors such as curvature of the earth, large bodies of water, and irregular surfaces affect the determination of centers of gravity, the following positions should be considered as approximations only] 1 Excludes islands adjacent to the conterminous United States. Excludes islands adjacent to the conterminous United States, but includes all islands of the Aleutian chain and Hawaii. Note.-The following distances in statute miles are computed to mean sea level: (a) from West Quoddy Head, Maine, west along the parallel to the Pacific Ocean, 2,807 miles; (b) from the south point of Texas due north to the 49th parallel, 1,598 miles; (c) from West Quoddy Head, Maine, to Cape Wrangell, Alaska, 4,839 miles; (d) from West Quoddy Head, Maine, to Kure Island, Hawaii, 5,788 miles; (e) from Mangrove Point, Florida, to Cape Wrangell, Alaska, 5,495 miles; (f) the two points farthest apart are Log Point, Elliot Key, Florida, and Kure Island, Hawaii, a distance of 5,852 miles; (g) length of the northern boundary, excluding Alaska, is 3,987 miles: (h) length of the Canadian-Alaskan boundary, 1,538 miles; (i) length of the Mexican boundary from Gulf of Mexico to the Pacific Ocean, approximately 1,933 miles, 1963 boundary agreement with Mexico; (j) the two points farthest apart in the conterminous United States are West Quoddy Head, Maine, and Point Arena, California, 2,897 miles; (k) the shortest distance between the Atlantic Ocean and the Pacific Ocean across the conterminous United States (approximately 10 miles south of Brunswick, Georgia, to approximately 12 miles south of San Diego, California), 2,088 miles: () Cape Mendocino, California projection extends to latitude 40°27', at longitude 124°24'; Cape Sable, Florida (on mainland) projection extends to latitude 25°07', at longitude 81°05′; Kure Island, Hawaii projection extends to latitude 28°25', at longitude 178°22′. The extreme south point of Texas is in latitude 25°50', longitude 97°24'. Source: Dept. of the Interior, Geological Survey; Boundaries of the United States and the Several States (bulletin 1212), MI0-18A; Geographic Centers of the United States, MI0-8; and unpublished data. No. 254. WATER AREA, OTHER THAN INLAND WATER, BY PRIMARY BODIES OF WATER-STATES [In square miles. Includes only that portion of body of water under the jurisdiction of the U.S., excluding Alaska and Hawaii. Excludes inland waters; see footnote 2, table 2521 Source: Dept. of Commerce, Bureau of the Census; Areas of the United States: 1940. Wisconsin. 726 2,675 [Comprises rivers 400 miles or more in length. Length represents distance to designated outflow from (a) original headwater of named river where name applies to entire length of channel, or (b) upper limit of channel so named, usually the junction of 2 tributaries or headwater streams] No. 256. AREAS OF SELECTED NATURAL LAKES [In square miles. Comprises lakes with surface area of 100 square miles or more] 496 Tom bigbee.. Mobile River. 409 625 Trinity.. Trinity Bay.. 715 2,348 Wabash Ohio River. 475 1, 171 Washita. Red River. 626 White (Ark.-Mo.). Mississippi River. 685 3,741 2. 315 Source: Dept. of the Interior, Geological Survey; Principal Lakes of the United States, Circular 476. |