This visualization shows the east to west spread of West Nile Virus across the continental United States from 1999 through 2002. The years are represented by different colors. This visualization was created in support of a story describing how NASA is assisting the CDC and EPA in tracking the spread of West Nile Virus. ||

These maps show mosquito habitat distribution for four mosquito species. The red/black areas are results of satellite data analysis showing where particular species of mosquitos can be found. The yellow lines are the 'published' boundaries for where these species can be found. There is a strong correlation between the two. These images were created in support of a story describing how NASA is assisting the CDC and EPA in tracking the spread of West Nile Virus. ||

The average temperature of the land is one component of a model used to predict the areas where mosquitos will flourish and where they will not. Satellite remote sensing can help construct maps of the average land surface temperature. These images were created in support of a story describing how NASA is assisting the CDC and EPA in tracking the spread of West Nile Virus. ||

The Normalized Differential Vegetation Index, NDVI, is one component of a model that is used to predict mosquito where mosquitos will flourish and where they will not. These images were created in support of a story describing how NASA is assisting the CDC and EPA in tracking the spread of West Nile Virus. ||

The colors on this map represent relative levels of risk for West Nile Virus in 2001, as determined by scientists with NASA's International Research Partnership for Infectious Diseases (INTREPID). The black dots on this map represent infected crows reported in 2001. Larger dots reflect a higher concentration of infected crows in one area.Credit data source: International Research Partnership for Infectious Diseases, INTREPID ||

A Risk Map depicts which geographic regions are at greater or lesser risk for some specific event or condition. This image represents a sample risk map for the West Nile Virus in North America. This image was created in support of a story describing how NASA is assisting the CDC and EPA in tracking the spread of West Nile Virus. ||

This animation was created in response to a White House request. It shows the distribution of the 20 million new jobs created since Clinton was in office. Horace Mitchell and Greg Shirah attended the press event where Clinton showed this visualization. ||

This animation shows the population density of the world in the years 1990, 1995, 2000, as well as a population density estimated for the year 2015. These figures have been adjusted to match United Nations totals. The most dramatic differences in population are not readily visible in this animation because they are located in cities. The maximum population density in 1990 was about 79,000 people per square kilometer, while the estimated maximum population density in 2015 will be about 236,000 people per square kilometer. Developing areas in Africa, Latin America, and Asia change the most visibly. ||

This image of Earth's city lights was created with data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Originally designed to view clouds by moonlight, the OLS is also used to map the locations of permanent lights on the Earth's surface.The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. (Compare western Europe with China and India.) Cities tend to grow along coastlines and transportation networks. Even without the underlying map, the outlines of many continents would still be visible. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. In Russia, the Trans-Siberian railroad is a thin line stretching from Moscow through the center of Asia to Vladivostok. The Nile River, from the Aswan Dam to the Mediterranean Sea, is another bright thread through an otherwise dark region.Even more than 100 years after the invention of the electric light, some regions remain thinly populated and unlit. Antarctica is entirely dark. The interior jungles of Africa and South America are mostly dark, but lights are beginning to appear there. Deserts in Africa, Arabia, Australia, Mongolia, and the United States are poorly lit as well (except along the coast), along with the boreal forests of Canada and Russia, and the great mountains of the Himalaya. ||

The mean center of population, traditionally referred to as the center of population, is provided for each census in the United States since 1790. The mean center of population is the point at which an imaginary, flat, weightless, and rigid map of the United States would balance if weights of identical value were placed on it so that each weight represented the location of one person. The mean center of population based on the 2000 census results is located in Phelps County, Missouri. For a complete list of the mean center of population for each census since 1790, and for a more detailed description of how these values are calculated, see http://www.census.gov/geo/www/cenpop/calculate2k.pdf. ||