Ask: How does population density vary?

Step 1: Go to the ArcGIS Online map, USA Demographics, and explore the map.

• Which part of the United States is the most densely populated? Zoom into the most densely populated area.
• What happens when you zoom in?

Step 2: Slowly zoom in on New York City or another urban area.

• What pattern do you observe?

Acquire: Why does population density vary?

Step 3: With the Details button underlined, click the button, Show Contents of Map (Content).

Step 4: Check the box to the left of the layer, USA Topo Maps.

Step 5: Make the USA Population Density layer 40 percent transparent. To view two layers simultaneously, make one “see-through.” In the Contents pane, click the three dots beneath the layer name. Select, Transparency, and adjust it to 50 percent.

Step 6: Zoom and pan the map.

• How does physical geography affect population density?

Explore: How does income vary across the United States?

Step 7: Turn on the two layers, Median Household Income, and USA Major Cities.

Step 8: Turn off all the other layers.

Step 9: Click the button, Show Map Legend (Legend).

• How are median household income and cities related?

Analyze: How does age differ across the United States?

Step 10: Click the button, Show Contents (Content).

Step 11: Turn on the layer, Median Age. Turn off other layers. Choose the bookmark, State.

• Which state has the highest median age?
• Which five states show young populations?

Step 12: Click the button, Bookmarks. Select, County.

• How did the pattern change?

Step 13: Turn on the layer, Median Age-UT & FL Tracts. Zoom to Florida.

• Are all residents in Florida elderly?
• What could account for the many elderly in Florida?

Act: How does scale influence the interpretation of data?

Step 14: Utah has the lowest median age in the United States. Click the button, Bookmarks. Select Utah tracts.

• At this scale, which bordering state shows the sharpest contrast?
• What is surprising about Idaho is that at the state level, it is has a low median age. But at the county level, it has a higher median age areas.

Step 14: Click the button, Bookmarks. Select Oklahoma City.

• What age patterns do you observe?

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