WHAT IS IT?

This model demonstrates what happens when Black families move into White neighborhoods and how communities can change over time. RED turtles, that are colored different shades of red based on their income, represent the Black families. For instance, DARK RED turtles represent families in the Black community who are rich; RED turtles represent families in the Black community who are middle class; and LIGHT RED turtles represent families in the Black community who are poor. The same color representations apply to the White families but the turtles are BLUE instead of RED.

There are three factors that determine whether or not turtles will move. The first factor is "tolerance," which is represented by a slider showing percentage and it can be increased or decreased. Therefore the higher the percent of tolerance a blue turtle has, the happier the turtle will be and the less likely the turtle will want to move. But the lower the percent of tolerance is for the turtle, the less happy the turtle will be and the more likely the turtle will want to move.

The second factor regards income. Black families' range of income is less than white families' income and Black families are not as likely as White families to receive raises in their income. Income for Blacks and Whites can be adjusted accordingly using the BINCOME or WINCOME sliders. If the BINCOME slider is adjusted to an income less than $150.00 then the turtle's color becomes light red as indicator that the turtle can not afford to move. However, if the BINCOME slider is adjusted to an income greater than $150.00 then the turtle's color becomes either red or dark red as an indicator that the turtle can afford to move. The same goes for blue turtles but unlike red turtles, blue turtles can move during any time period as long as they can afford to move.
[Note: to live in the white community within the city, a house sells for $200.00 and in the suburb a house sells for $300.00. Therefore, red or blue turtles can not afford to move into new homes if their income is below house values.]

Thus the third factor deals with time. Depending on the time period, which is represented by the TIMELINE slider, dark red or red turtles will be able to move out of the Black community and into the white community [or the suburb.] Blue turtles on the otherhand can move whenever they want regardless of time as long as they can afford to.

HOW TO USE IT

Click the SETUP button to set up the turtles. There are equal numbers of black and white families. The turtles move around until there is at most one turtle on a patch or one family in a house. Click GO to start the simulation. If timeline is set after 1950 and turtles can afford to move then they will move with the exception of white turtles that can move from the city to the suburbs regardless of the time period. Also, if white turtles have a certain percentage of black turtles as neighbors, they will move to a different patch in another community.

The # of BLACKS and the # of WHITES' sliders control the total number of turtles that can be created. Note these sliders will take effect the next time you click SETUP. The TOLERANCE slider controls the percentage of red turtles that live nearby blue turtles. For example, if the slider is set at 25, each blue turtle will look to see if 25% ofits neighbors are red turtles. If this is occurs, then the blue turtles will move to different patches in different communities to get away from red turtles.

The RES-BLACK monitor shows the number of red turtles that are living in the black community, the BLACK-WHT monitor shows the number of red turtles that are living in the white neighborhood [within the city,] the WHITE CITY monitor shows the number of blue turtles that are living in the white community within the city, and the WHITE SUBURB monitor shows the number of blue turtles living in the suburbs. The values of these monitors are graphed and can be seen in the plot windows.

Other monitors include the HOUSESFOR SALE monitor which shows the number of houses that go up for sale. (Note the houses are represented by orange patches). The BLACKSWANTMOVE monitor shows the number of dark red turtles who can afford to move and want to move out of the Black community. And the MOVES monitor tallies the amount of times the simulation goes through to find a turtle that can afford to move.

Also note that patches in this simulation are important. If a patch is grey in the Black community (big brown patch) then that means a house is for sale. If a patch is purple in the White community, (big white patch) then that means a house is for sale. If it's post 1950 and a red turtles is on a patch that is magenta, then that means that turtle can afford to move but doesn't have anywhere to go. Red turtles will only move to the suburb (big green pactch) after 1980. If patches are magenta in the suburb(s) then that means there are houses for sale.

THINGS TO NOTICE

In this model there are several variables that affect when a turtle moves. Look for patterns in how these variables affect the moving of white families. What variable has the greatest effect and why? Does the use of the variables make sense when comparing the model to real life occurrences of "white flight?" Why or why not?

Notice what colors turtles are before they move. What does that say about the economic status or value of communities with these colored turtles? Notice the color of the remaining turtles in the "black" community. What does that say about the economic status of that community or neighborhood?

THINGS TO TRY

Set the TIMELINE to 1950. Describe what happens to the black community and white community. Gradually increase TIMELINE as model runs. What happens to the existing communities? Why does a new community form? Hypothesize what you think will happen to the new community over time and describe how that will impact the flow of the model.

Make a table that has two columns. In the first column list the percent of "TOLERANCE" a blue turtle has beginning at 25% and increasing by increments of 25% until you reach 100%. In the second column, record the "# OF MOVES" reported by the simulator. Explain why number of moves changes based on your table.

EXTENDING THE MODEL

Notice this model has a lot of space in the suburbs that's not occupied by homes with families. Extend the model so that more space in the suburbs is occupied by homes with families and a new community develops.

Now that a new suburburbian community has developed, extend the model so that white families within the new suburban community move into the black community causing "gentrification." If this occurs what happens to the value of homes in the black community? What happens to black families who still may live in the Black community? Will they move? If so where and why?