While we make use of many varieties of data, our primary sources come
from county tabulations drawn from the U.S. censuses of population
and agriculture. We have collected those data for the decennial
population censuses from 1880 through 2000, as well as for the
agricultural censuses (which were decennial until 1920 and then more
frequent thereafter) from 1880 through 1997.3 In addition to
census-based sources, we have collected other county-level
tabulations of social characteristics. We use the population and
social indicators data to understand population structure and
change, and the agricultural census data to understand agricultural
land use. Their consistency, as well as the effectiveness and
long-term quality of the U.S. census, have made this part of our
project straightforward. Some of these data were available to us in
digital form, and others we collected in print form and then
hand-keyed into our database. All of these data are described in
Gutmann et al.
(1998). Since that document was published, we have added
data from recent censuses (1997 agriculture and 2000 population),
while maintaining their content and structure. Although our study
area is not coterminous with the 10 states, we have collected data
that covered the entire area of the 10 Great Plains states, and
often neighboring states, especially Iowa and Minnesota.
Answer choices for the question?
Answer:
The Ecosystems that show where early civilization occurred are Savannah and Rain forest Ecosystems because the areas allowed people to grow crops even during the time of little rainfall.
Explanation:
Savannah Ecosystem actually started as rainfall inadvertently reduced around the tropics during the olden days especially between 66 million to 25 million years ago according to various resources available. The most dominant vegetation in the Savannah nowadays are grasses apart from the covered trees. Even the grasses must have appeared about 50 million years ago although there may be some possibility that some Ecosystems like Savannah may have existed earlier than that. From various online resources, it is evident that the first human to appear on earth may have appeared in the SAVANNAH REGION of Africa after which he ensure various resources in the environments were modified before moving and spreading to other continents.
However, the Rain forest region is the ecosystem that usually occur in high annual rainfall areas all around the earth.The trees are of broad leaves and always evergreen. The ares are mostly with one river or the other e.g Nile River, Amazon River, Congo River. This Ecosystems must have been in existence for over 500 million years according to various researches thus giving credibility to the fact that it is among the two Ecosystems that ensure early civilization all year round just like Savannah Region with low level of rainfall then.
Answer:
In Lincoln's mind, the railroad was part of the Civil War effort. The new line would support communities and military outposts on the frontier. ... A transcontinental railroad, Lincoln hoped, would bring the entire nation closer together – would make Americans across the continent feel like one people.
Hope this helps
