Exploring A Century of Population Change Across the United States with GIS:  Answer Key

Make the themes visible by checking on the box to the left of the theme name.

25)  How many records are in this table?

[ 3,140 ]

26)  Is this more, less, or the same number of records as the attributes of county20thcentury table? 

Then:  Theme --> Convert to shapefile.

Name the shapefile “countyall.shp” and place it in your folder containing your other data for this project.

^{Add the new shapefile into your view.}

^{30)  Does this new shapefile have the same number of records and fields as the one you have just been working with?  Why or why not?}

[ Yes  - same number of records because the new shapefile was created from the old file with the join. ] 

^{Make county20thcentury the active theme by single-clicking on it.}

^{Now, delete the county20thcentury theme.  Edit-->Delete theme.}

^{31)  Why are you safe in deleting this theme?}

^{1900 Analysis}

^{Change the legend and make a map of 1900 county population.}  

^{Access the table.  Use field statistics.}  

^{32)  What was the USA population as indicated by the sum of all the county populations in 1900?  Use Field Statistics after clicking on the 1900 population field.}

[ 75,541,434 ] 

^{Sort by 1900 county population.}     

^{33)  What was the county with the highest population in 1900?}

[ New York, New York ] 

^{On the map, use the "zoom to selected" button to zoom to that county.  Use the label tool to label the county and those around it.}

^{34)  Why was this county's population so high in 1900?  Anchor your answer to a discussion of immigration to the USA in 1900 and the point of arrival for most immigrants.}

[ Many immigrants were arriving from Europe, entering the USA through New York Harbor at Ellis Island. ]

^{Analyze how this county has changed in population from 1900 to 2000 by creating a graph of its population.  In the project window, go to Charts--> New.  Give your chart a title, and, one by one, add the following fields to the chart: P1900, P1910, P1920, P1930, P1940, P1950, P1960, P1970, P1980, P1990, and P2000.}  

^{35)  Print your graph and answer the following questions:  How has this county changed in population over the past century?  Why did the population decrease from the early until the latter part of the 20th Century?  Why did the county start increasing in population?  Anchor your discussion in internal migration, metropolitan suburbanization, changes in employment and economy, and gentrification.}

[ New York county's largest increase in population was in 1910 as immigrants from Europe entered the USA at New York.    People started to migrate from New York to other parts of the country in the 1920's.    The Great Depression  started in 1929 took a toll on the number of jobs in New York.  People migrated to other areas to find work.      At the same time fewer and fewer immigrants were entering the US as a result of WWII.     The slight increase in the 1950s was a result of the Baby Boom generation being born.  Fewer immigrants were coming to the US from Europe.   The 1960's through 2000 saw people moving from the cities to the surrounding suburbs or moving to other areas of the country.      Many New Yorkers moved to the warmer Sun Belt states as they  moved into their retirement years.  After 1980, some gentrification and a back-to-the central city movement in many cities, including New York, brought some population increases.  ]

^{36)  Select two other center-city metropolitan counties such as Harris County, Texas, St Louis County, Missouri, and Wayne County, Michigan, make a graph of their population changes, and compare the growth of these counties compared to the county you examined in question 33.}

[  Wayne County Michigan is where the City of Detroit is located.   Detroit is the Motor City of the World, home to the American automobile industry.    As the manufacturing of cars in creased in the 1920s, so did the counties population.     This growth continued in the 40's, 50's, 60's, 70's, and 80's.    The population of Wayne county started to decline as people moved from the county to the surrounding counties away from the city of Detroit.   Starting in the 1980's  the  American automobile companies lost market share  to foreign manufactures which resulted in the closing of many plants.    Wayne County has not seen the increases common in other cities after 1980 with the return of people to the central city.  ]  

^{Analyzing 20th Century Change}

^{Clear your selection and use the procedures you learned above to answer the following questions:}

^{37)  What USA county had the largest population in 1950?}

[ Cook County, Illinois ]

^{38)  What USA county had the largest population in 2000?}

[ Los Angeles, California ] 

^{39)  Describe the direction of population change from 1900 to 2000 across the United States as evidenced by the county with the largest population in 1900 vs 1950 vs 2000.  Why did the population move the way it did?}

[ The population of the US spread  from the East cost to the West coast.    When people first immigrated to the USA, they first stayed in New York.  As more jobs became available they moved to the Midwest.   California attracted growth because of the growth of technology in the state and its warm climate. ]

^{40)  Make a graph and describe how the population of Todd County, South Dakota has changed from 1900 to 2000.  What influence do you think do Native Americans have on the historical and current population of the county?  Why?}

[ Todd County grew over the years, but not as rapidly as other counties, due to its rural nature.  Native Americans (because of their larger families, university, and tribal government, providing some job opportunities, have ensured that the county did not decline in population as other counties have done in the region.  ]  

^{Access the table .  Use the field-->summarize tool to answer the following question:}

^{41)  What was the USA population as indicated by the sum of all the county populations in 1950?}

[ 150,903,212 ] 

^{42)  What was the USA population as indicated by the sum of all the county populations in 2000?}

[ 281,415,622 ] 

Even though the population of the entire country increased, not every county necessarily increased.  Use the query tool to find out which counties had more people in 1900 than they did in 2000:  

Use the following formula:  ( [P1900] > [P2000] )

43)  How many counties were selected?

[ 688 ] 

44)  Do these represent counties that are growing or counties that are declining?

[ Declining ] 

45)  How many of these counties are in South Dakota?

[ 28 ] 

46)  Describe the pattern of the counties that decreased in population over those 100 years:

[ Most of the counties that declined are rural, although some central cities are also included.  Most are agricultural, although some mining counties are included.  The pattern is focused on the Great Plains, and in particular, the Upper Midwest. ] 

47)  Indicate at least two reasons why the counties have decreased in populations according to the pattern you identified above.

[ People have left these areas because of lack of jobs.    People have left these areas for warmer climates.  People have moved from the farms or mining to service jobs, manufacturing jobs, or to centers of technology.  ] 

Clear the selected set.  

Using the above procedures, do the same thing for 1990 versus 2000 counties.

48)  How many counties had more residents in 1990 than they did in 2000 ?

[ 683 ] 

49)  How many of these counties are in South Dakota?  Compare this to the number you indicated above that lost population over the previous 100 years.

[ 32 are in South Dakota.  More counties continue to lose population than gain, because the state is predominately rural.  The urban counties are gaining, as well as most Black Hills area counties; the state as a whole is gaining. ]

50)  Compare the number of 1990 vs 2000 decreasing counties to your 1900 vs 2000 number above, and compare the spatial pattern of each set.  Indicate two similarities and two differences between the 10 year pattern and the 100 year pattern.

[ To perform this analysis, you may want to duplicate the countyall.shp file and run the query shown in question  43.        Similarities -   Again the plain states saw population loss.   Counties continue to gain and lose population over time.        Differences -  More counties in New England are showing loss.  The loss of population in the  Upper Great Plains states has increased.    The number of counties showing loss is moving further West.]

51)  Describe at least two characteristics of the pattern of county population that you believe will exist in the USA in 2100, and give at least two reasons for your prediction.   

[ The loss of population in counties will continue to move westward.    As the Baby Boom generation ages, warmer counties will lose population.    As the country also ages, more Midwest counties will lose population. ]

52)  Clear selection and create a United States map of the change (the second to last field in the table) in population from 1990 to 2000.  Make at least two observations of the resulting pattern.  

[ This is raw number change.   The counties with the most change are located in the states of Florida, California and Arizona, but other states also appear.   ] 

53)  In the table, sort by the population change.  Which three counties gained the most population from 1990 to 2000?  

[ Maricopa, Arizona              Los Angeles, California            Clark Nevada ] 

54)  In which states were they?  Do the results surprise you?

[ Arizona, California, and Nevada.  These are the warm weather states; people move here from the East and Midwest states. ] 

55)  In the table, sort by the population change.  Which three counties lost  the most population from 1990 to 2000?  

[ Baltimore City, Maryland             Philadelphia, Pennsylvania          Allegheny, Pennsylvania ] 

56)  In which states were they?  Do the results surprise you?

[ Maryland and Pennsylvania.  These  areas have lost manufacturing jobs so people have moved elsewhere. ] 

57)  Clear selection and create a United States map of the percent change (the last field in the table--percent) in population from 1990 to 2000.  Make at least two observations of the resulting pattern.

[ The Great Plains states show the highest percentage of negative change.  The Western states of Nevada, Utah, Arizona, and Colorado show some of the highest rates of positive change.    The Southern States show moderate rates of positive change.   ] 

58)  Compare the percent change map to the raw population change map and make at least two observations of the differences and similarities between numeric change and percentage change.

[ They both show that the states with the greatest amount of change are in the Western States of California, Nevada, Colorado and Arizona.   The Great Plains states show slow rates of positive and negative change. ]

59)  In the table, sort by the percent change.  Which three counties gained the most in percent from 1990 to 2000?  

[ Douglas, CO       Forsyth, GA      Elbert, CO ] 

60)  In which states were they?  Do the results surprise you?

[ Colorado and Georgia.  Answers will vary.  Not surprising - natural amenities in Colorado, suburban expansion along Colorado Front Range and in suburban Atlanta. ]

61)  In the table, sort by the percent change.  Which three counties lost  the most population in percent from 1990 to 2000?  

[ Aleutians West, AK         Loving, TX      Esmeralda,  NV    ] 

62)  In which states were they?  Do the results surprise you?

[ Answers will vary.  Loss of military or fishing jobs in Alaska.  Mining job loss in Nevada.  Rural population loss in Texas, coupled with the very low overall population of Loving County to begin with. ]

Creating New Data:  Dust Bowl Analysis

Thus far, you have been working with existing data.  A GIS also allows you to create new data and analyze it.  You are working for the US Natural Resources Conservation Service, and wish to examine the population change from 1930 to 1940, focusing on the Dust Bowl period when many people left farms across the Midwest during a series of dry years. 

Go to Table--> Start Editing.   

Go to Edit--> Add Field.

Make your new field named p30vs40, a number, with 16 width and 2 decimal places.

63)  Select the calculate button and calculate the values in your new field.  What expression should you use to obtain a percentage change from 1930 to 1940? 

[ ((1940 - 1930) /  1930) * 100) ] 

Select Table--> Stop Editing and save your edits.

64)  Make a graduated color map of your new field and make two observations about the pattern of population change across the country during the 1930s.

[ The Great Plains states showed a decrease in population with the Western states picking up population, particularly California, as many Midwesterners moved there to find work.  The Midwest states showed heavy losses due to farm depopulation; the Southern states showed some growth.  ]

65)  Based on your observations, which state would you say that most of the displaced farmers from the Midwest moved to during the 1930s?   If time permits, read sections of The Grapes of Wrath by John Steinbeck.

[ Most headed west, to California, and some to the Southern states.]

South Dakota 

Next, you want to focus on South Dakota counties.  Clear any selections and use the query builder to select only counties in South Dakota. 

66)  What expression did you use to select South Dakota counties?

[ ([state_name] = "South Dakota") ] 

67)  How many counties are selected?

[ 66 ] 

Use Theme--> Convert to shapefile to save your South Dakota counties into its  own data set.  Name it sdcounty.shp and place it in your folder.

68)  Access the table for your new theme.  How many records are in its table?  

[ 66 ]

69)  Why?

[ Because you created a new shapefile based on your original selected counties. ] 

Change the legend for South Dakota counties to a CHART legend type.  Your goal is to create a pie chart in each county that indicates the relative percentage of Native Americans in each county.  Add the fields pop1990 and Ameri_es to the right side of the box, to create a pie chart of Native Americans and total population in each county.  Under "properties," change the size field to Pop1990 and Apply.

70)  Describe what happened.  

[ The circles changed in size to show the counties where the largest populations are located.  Inside each circle a slice  was made to show of the percentage of the county population that is Native American.] 

71)  Does the chart map aid your understanding of Native American and Total Population distribution in South Dakota?  Why or why not?

[ Yes, the charts show the pattern of American Native populations in South Dakota. ] 

Experiment with the colors, sizes, and with other data in the chart map legend.

Go to View--> Layout and make a layout of your map.  Print the layout. 

Clear selections.

Save your project. 

Three Dimensional Analysis

Three dimensional analysis can aid in understanding many types of geographic phenomena.

If you have the 3D Analyst extension, complete the following section to analyze county population change in three dimensions.  If you do not have the extension, skip to the second last question of this lesson.

Go to File-->Extensions, and turn on the 3D Analyst extension.  Next, in the project window, click on 3D Scene, and select New.

Add your countyall.shp data to the 3D scene.  Make a graduated color map of the field "percent."   Make the breaking point between the first and second categories a zero (0) by clicking in the legend itself and typing the new value.  Be sure to end category 1 at zero, and begin category 2 at zero.   In other words, the first category will represent the decreasing counties, and categories 2 through 5 will represent increasing counties. 

Next, go to 3D Scene --> Properties, and change the background color from black to white.

Next, go to Theme--> 3D Properties.  Extrude features by the following expression:  [Percent] / 7

Apply and rotate and zoom around your 3D map of population change from 1990 to 2000.  

72)  Make two observations of the pattern of population change in the southwest USA--Arizona, Nevada, and California.

[ Answers will vary.  The change is greatest in southern Nevada and Arizona, but some counties are stagnant or even decreasing. ] 

73)  Rotate the map so that you are looking south from Canada into North Dakota.  Make two observations of the pattern of population change in the Midwest USA--the Dakotas through Oklahoma.

[ The Midwest rural counties usually decreased, with some urban counties showing an increase.  ]

74)  Make two additional observations about population change in the USA.

[ Answers will vary.  Florida shows an increase.  Texas panhandle decreased, but Central Texas is characterized by high growth.  Colorado is characterized by high growth in the Central part of the state, decreasing population in the plains section. ]

75)  Summarize in a few sentences what you have learned about population changes in the United States over the past 100 years in this lesson.

[ Answers will vary.  Population change is highly variable between rural and urban, and even among cities, and between regions. ]

76)  Summarize in a few sentences what you have learned about GIS in this lesson.

[ Answers will vary, and could include querying, selection, 3D analysis, sorting, analyzing patterns, charts, layouts. ] 

Save your project and exit ArcView GIS.

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