The Transcontinental Railroad innovation had the GREATEST impact on westward migration immediately after the American Civil War.
After the Civil War, there was great interest and opportunity with westward expansion. With the invention of the railroad, the transport of goods and people became quicker and less expensive than ever before.
The population of Georgia has increased since then. Pretty much everywhere in the world the population is always increasing.
The correct answer is: "all money earned in the course of a year".
Income is a flow variable, which means that it can be measured over a period of time, which in this case is typically measured for a year.
Income is an economic term which is defined as the set of all remunerations earned by an individual from any factor of production (land, labor, capital) sold in the factor markets. The types of income are: rent (remuneration for land), interest (remuneration for capital) and wage (remuneration for labor).