This map is showing the percentage of black in the US on the basis of counties in 2000. Notice that high percentage counties, from 50% up to 86.5%, are mainly located on the southwest coast due to historical event of immigration. Since the map is based on percentage, there are counties that only have several thousand people, but a huge percentage of black, whereas some big counties have huge population, but a small percentage of black. In other words, the deeper color does not imply greater number of black directly.
This map is showing the percentage of Asian in the US on the basis of counties in 2000. Notice that the main portion of Asian, from 10% up to 46%, is distributed along the west coast(mainly California), the Mississippi river and some parts of the east coast. The high percentage on California makes sense: we see a lot of Asians in our school every day! The high percentage on the Gulf of Mexico resulted in the immigration of Asian refugees from the World War II.
This map is showing the percentage of some other race in the US on the basis of counties in 2000. As indicated by the definition provided by the US Census, this category mainly consists of Hispanic and Latino Americans such as Mestizo and Mulatto. This is not a standard category since it depends on how the prior categories are defined. Notice that high percentage of some other race, from 15% up to 40%, is distributed on the southwestern part of the country.
Overall, this project is based on data from 2000 US Census. Notice that the legend scale of each map is made to be different because of concerns of clarity. From the scales we can conclude that among those three categories, black has the largest proportion of people in the US. There are some counties that are “blank”, indicating that no one of that certain race lives in that area. Interestingly, same for all three maps, the coast is where large portion of immigrants live and thus large percentage of those race.
ArcMap is really helpful in combining graphics with data. Data can be collected county by county and presented in a table (either in the form of .xls or .dbf). Also, ArcMap makes it possible to convert xls files into dbf files and then apply it to the county layer. When I was joining attribute table of the county layer to the 2000 Census data I found out that in some counties, the percentage of certain race is presented to be “null”. This is because those counties do not appear on the raw table (.xls), indicating that no one of that race lives in that area.
No comments:
Post a Comment