in recent decades as manufacturing has moved away from Detroit to factories in the southern United States, Asia, and Latin America. These shifts, as well as technological change such as the increased use of robotics, impact the quantity and types of employment. Photo by Xieyuliang. Stock photo ID: 587205803, Shutterstock.
Figure 1.2.Geographers also study demographic patterns. Fertility rates vary greatly from place to place. Large families can still be found in much of Africa and the Middle East, while smaller families now dominate North America, Europe, and much of Asia. Photo by Avatar_023. Stock photo ID: 23509669, Shutterstock.
ArcGIS Online mapping service
Given that the guiding principle of geography is understanding where things are located and why they are there, the map is an essential tool. While people have used maps for millennia, in recent decades maps have evolved from being static and drawn on paper to being dynamic and digital. This book examines a wide range of geographic issues, drawing heavily on the power of Esri’s ArcGIS Online digital mapping service (figure 1.3).
ArcGIS Online is a powerful cloud-based system that allows users to explore and analyze thousands of geographic datasets. Traditional data, in the form of text and spreadsheets, becomes immensely more useful by adding a spatial component via maps.
For instance, by mapping a conventional list of customers’ addresses, it becomes possible not only to visualize where customers live but also to identify neighborhoods where few or no customers reside. Analytical tools can further enhance an understanding of customers by mapping statistically significant hot spots, where clusters of customers live, and cold spots, where few customers live. By detecting these patterns, it is then possible to look at underlying social, economic, and environmental characteristics of the hot spots and cold spots. Additional data can be added to the map, which may indicate the cold spot is due to concentration of a distinct immigrant group. On the basis of this geographic information, a site-specific marketing campaign can be developed to appeal to this group.
In this book, most maps are produced with data from ArcGIS Online. This allows students and instructors to not just view maps in a static, printed, format, but to explore them in more detail in ArcGIS Online. In addition, each chapter includes ArcGIS Online exercises, where you will explore geographic datasets with sophisticated analytical tools.
Given that this book is built around ArcGIS Online, before moving on to more detail on the discipline of geography, it is important to first understand how maps function and how new digital technologies are reshaping the way geographers study the world.
Geographic tools and data
Geospatial technology
The traditional tools that geographers have used throughout history have gone through a dramatic transformation with the development of geospatial technologies. These are digital technologies developed in recent decades that allow geographers to collect data about the earth and run sophisticated analyses. With global positioning systems (GPS), remote sensing, and geographic information systems (GIS), vast quantities of data about human and natural features can be collected with great precision and analyzed with sophisticated techniques. Most people are not even aware that these geospatial technologies have become an integral part of our lives. Your cell phone can track your location with GPS, while Google Maps provides vast quantities of satellite imagery and geographic data on roads, businesses, parks, public buildings, and more. Based on this information, it is possible to determine where you are, then calculate the fastest route from your location to a coffee shop, or to find not just any local coffee shop but a coffee shop with a high customer rating.
Figure 1.3.This book is designed around ArcGIS Online. Access ArcGIS Online at https://www.arcgis.com. Image by Esri.
GPS is a powerful technology that identifies the location of a receiver unit (such as your cell phone) on the surface of the earth. Created by the US Department of Defense to aid in precision targeting and navigation, the system relies on three components: a receiver unit, a constellation of satellites, and ground-based tracking stations (figure 1.4). A system of twenty-four satellites circles the globe, and the precise location of each satellite is tracked by ground stations. GPS receivers communicate with satellites by sending and receiving radio waves. The time it takes for radio waves to travel between the receiver and a satellite is used to calculate the distance between them. With a minimum of three satellites, a two-dimensional location (latitude and longitude) on the earth’s surface is determined. With at least four satellites, a three-dimensional location (latitude, longitude, and altitude) is determined. Based on this system, a GPS receiver works only when it has a clear line of sight to satellites and thus is of limited use indoors. However, many cell phones use technology that compensates for this limitation by using Wi-Fi and cell tower connections with known latitude and longitude coordinates to determine location.
Figure 1.4.GPS systems consist of a receiver unit, ground control stations, and a constellation of satellites. Ground control stations track the precise location of satellites. Location is determined by measuring the time it takes radio signals to travel between a receiver unit and satellites with known locations. Image by Art Alex. Stock vector ID: 532342483, Shutterstock.
The most common use of GPS is for navigation. You use GPS technology every time you use Google Maps on your phone to identify where you are and where you need to go. GPS also assists navigation for aircraft, ships, and ground vehicles. But GPS receivers are also powerful tools used for field data collection. Many GPS units allow for the collection of data as points, lines, and areas. An urban arborist can collect point data on trees, taking note not only of each tree’s location but also of information on the species, height, health, and more. A surveyor can collect line data on property boundaries and roadways, with associated information on owners, condition, material, and so on. A biogeographer can collect data on areas of illegal logging, noting where the logging has occurred as well as the time period and type of species that is being stolen.
Another important geospatial tool is remote sensing. Remote sensing consists of images of the earth’s surface, typically taken from satellites or aircraft (figure 1.5). Passive remote sensing instruments mounted on these platforms read reflections of the sun’s radiation or heat emitted from the earth’s surface. Different types of features, such as asphalt, cement, water, soils, rocks, and vegetation types, all reflect radiation differently, thus giving features a unique spectral signature. Active remote sensing instruments emit energy, such as with a laser or microwaves, which bounces off features, showing their location and shape.
Figure 1.5.The Landsat-7 satellite, operated by the US Geological Survey. Satellites and aircraft are common sources of remote sensing imagery. Image by NASA.
One of the most common uses of remotely sensed imagery is for basemaps, as used in digital maps such as ArcGIS Online. However, imagery goes well beyond simple basemaps. By analyzing the spectral signature of features, areas can be classified, such as in a thematic map of land use/land cover that shows urban areas, forests, different crop types, and more (figure 1.6). Remote sensing is also used for economic research by looking, for example, at the number of cars in retail parking lots and viewing tanker railcars at oil refineries. In environmental monitoring, it is used to track oil spills and determine the health of forests. Local governments use remote sensing to study urban growth and transportation needs. International aid and human rights organizations use it to help evaluate the condition of refugee settlements or to identify areas with mass graves
