The railroads :)
<span>Especially in 1848, when workers began to build the Galena & Chicago Union Railroad. </span>
<span>Here's some info. http://encyclopedia.chicagohistory.org/pages/653.html
Hope this helps</span>
Legislative, Executive, Judicial
Answer:
A testable proposition.
Explanation:
A hypothesis is one of the tools in working in different academic settings. It is used in the both science, social science and art fields.
It is defined here to be simply a proposition that is testable or it can also be defined as a proposition, or set of propositions, set forth as an explanation for the occurrence of some specified group of phenomena, which is either asserted merely as a provisional conjecture to guide investigation or accepted as highly probable in the light of established facts.
Human environment is greatly influenced by the ecosystem and nature.