Image from usatoday.com
The migration of the American population from rural areas to urban areas has occurred for many years. Both US census data, and the USA today chart that is derived from that data demonstrate this decline in percentage of the total population.The USA Today graphic is called a snapshot, and is one of many featured in every issue of the newspaper. These snapshots are, according to usatoday.com, "easy-to-read statistical graphics that present information on various issues and trends in a visually appealing way." The example above is clearly easy to read and visually appealing. There are only a few numbers on the graph; just enough to assure the reader that this chart is legitimate. The lines are bold and straight making them easy to follow. Even the colors are appropriate, with green representing the natural, rural farmers, and the gray representing the city and its dark streets and buildings. These colors contrast each other well, which makes it easy to see the increasing gap between the urban line and the rural line. After looking at this chart for a few minutes, which is probably longer than any USA Today reader would, I noticed that the graph was not mathematically accurate. The slopes of the two lines should not be constant, but should change to become steeper after 1960. The general idea is still expressed with the lines, but more could be gained if the graph was more accurate, particularly if there was more data.
Data from census.gov
The US census data, from the 1990 US census, shows percentages and total populations living in rural and urban areas. The full data set also tracks rural and urban population shifts in every state. This information can be found here. Urban and rural population shift is an interesting phenomenon that can be examined easily with the census data. The representation of the data in this chart form is not exactly how it appears on the website. I omitted the data for the individual states in order to make it easier to read and fit on the page better. Even with all of the extra information removed, it is not that easy to parse the data. The formatting of the chart, with a separate label for every single number on the chart makes it difficult to draw connections between different pieces of data in order to recognize trends in the data. I reformatted the data into a new chart. The major change I made was removing the single row method from before. All of the data is from the United States, so there is no need to label that it is. With the data formatted this way it is much easier to see how the data trends over time. After looking at the data in this format I noticed that the rural population was increasing even though the percentage is decreasing. The USA Today graphic only discussed the changes in the percentage of people living in rural and urban areas and stated that "a steady decline in rural populations was first noted in the 1920 census."The formatted data makes it easy to see the deceptiveness of the graphic. Because we are given an incomplete picture USA Today is able to manipulate us to project the knowledge that they want to impart on us. I'm not sure why they would want us to believe that urban migration is so big, but it definitely is deceiving. It seems as if USA Today wants us to think that the rural population is fleeing to the cities at a rapid rate.
Confused by the snapshot, I decided to plot the data using Matlab, in order to see if there was any intentional deception from USA Today.
The first graph is the percentage rural and urban, and the second is the uses the actual population numbers. The first graph should look the same as the USA Today chart, and it does look similar. But not the same. I used the data supplied by the US census to create by charts and used 10 data points instead of three. Also I plotted them accurately, so the slope of each segment is accurate. The steepness of the slopes generally appears to decrease over time, which means that migration to urban areas is decreasing. This differs from the USA Today graph that shows constant migration over 80 years. If we look back at the comment, saying "a steady decline in rural populations was first noted in the 1920 census" we can see how wrong it is. Even if it is referring to the percentage rather than the population, the decrease was happening 20 years before that, and at one of the fastest rates in the last 100 years! The second graph confirms what we saw in the earlier data. We can see that both the urban and rural populations are increasing, although the urban population is increasing at a faster rate. One significant part of the graph is that it is easy to see how the urban population growth mirrors the total population growth. This means that the total population growth depends on the urban population growth rather than the growth in the rural population, which is too small to make a significant impact on the change in total population.
The new graphs shed even more light on urban migration than the charts. The graphs make it easier to understand trends than with the charts. You do lose a little using the graphs because it is difficult to know exact values just by looking at the graphs. Even though you have more accurate data with the charts pattern recognition is done by keeping track of values and trends mentally rather than visually, which can be difficult to do. In this example I think it is more important to understand the trends and patterns of the situation rather than actual data values, which leads me to believe that graphs are more useful in this situation. I do hesitate to say that, because we have seen how deceptive these charts can be when we looked at the snapshot from USA Today.




