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State Borders

Run the State Borders MicroSim Fullscreen

About This MicroSim

Every line where two states meet is colored by the kind of border it is:

  • River borders (blue) follow rivers such as the Mississippi, the Ohio, and the Rio Grande.
  • Lake borders (light blue) run through the water of the Great Lakes and Lake Champlain.
  • Mountain borders (brown) follow ridges such as the Bitterroot Range and the Appalachians.
  • Straight-line borders (red) were drawn by lawmakers and measured by surveyors. Many follow a line of latitude or longitude.

Turn the natural borders or the straight-line borders off to see each kind by itself. A pattern jumps out: the East is full of wiggly river and mountain borders, while the West is mostly straight lines.

Five gold stars mark special places: the Four Corners, the "rectangle states" of Colorado and Wyoming, the Oklahoma Panhandle, Michigan's two peninsulas, and West Virginia's odd shape.

How to Use

  1. Hover over a border to see which two states it divides.
  2. Click a border. The panel under the map names the river, mountain range, or line it follows and explains why the border is there.
  3. Click Natural Borders or Straight-Line Borders to turn that color off and on. Borders that are turned off become thin gray lines.
  4. Click a gold star to read about a special place. The states involved turn yellow. Special Places hides or shows the stars.
  5. Click Quiz Me! for six questions. One border turns gold and you decide whether it is a natural border or a straight-line border.
  6. Reset returns the map to its starting view.
  7. Use the + and - buttons to zoom in on the small states of the Northeast.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

<iframe src="https://dmccreary.github.io/us-geography/sims/state-borders/main.html"
        height="642px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

Grades 3-6

Duration

15-20 minutes

Learning Objective

Students will distinguish between natural and straight-line borders and explain why borders are located where they are (Bloom's level: Analyze).

Prerequisites

  • Students know that a border is the line where one state ends and another begins.
  • Students have seen lines of latitude and longitude on a map.

Activities

  1. Exploration (5 min): Students turn off Straight-Line Borders and describe where the natural borders are. Then they switch, showing only the straight lines. Ask: Which half of the country has more of each kind?
  2. Guided Practice (7 min): Students click the Mississippi River border, the Ohio River border, the 37th parallel, and the Idaho-Montana mountain border, and read the "Why here?" explanation for each. As a class, sort the reasons into two lists: "nature made the line" and "people drew the line."
  3. Assessment (5 min): Students take the six-question quiz. Then each student picks one border and explains in a sentence or two why it is where it is.

Discussion Questions

  • Why do you think the western states have so many straight borders?
  • What makes a river a good border? What problems could a river border cause?
  • Colorado and Wyoming look like rectangles. What kind of lines make up their sides?
  • Find a state with borders of three different kinds. Which state did you pick?

Assessment

  • Student classifies a highlighted border as natural or straight-line.
  • Student names the river or mountain range that a natural border follows.
  • Student explains one reason a border was placed where it is.

Data Notes

  • The border lines are the shared edges of the Natural Earth 110m state shapes, so they are simplified. A river border on this map has fewer bends than the real river.
  • Some real borders are a mix of short pieces. Each piece on the map is labeled with its main type.
  • Borders measured by colonial surveyors are shown as straight-line borders even though old tools left them slightly crooked.
  • One border piece is neither natural nor straight: the curved Twelve-Mile Circle between Delaware and Pennsylvania, shown in gray.
  • The Rio Grande between Texas and Mexico is included because the chapter describes it. It is a border between two countries, not two states.

References

  1. Natural Earth - Public domain map data used for the state shapes and border lines.
  2. Boundaries of the United States and the Several States - U.S. Geological Survey Bulletin 1212, the standard history of how each state border was set.
  3. Four Corners Monument - Navajo Nation Parks and Recreation.
  4. Mason-Dixon Line - Encyclopaedia Britannica.
  5. Leaflet - The open-source JavaScript library used to draw the map.