Protective tariffs were a key element of the American system. These are tariffs that are enacted aiming to protect a domestic industry. Protective tariffs seek to make imported goods cost more than equivalent goods produced in the country, leading to the rise of sales of domestically produced goods; supporting local industry. Tariffs are also imposed in an attempt to increase government revenue, or to reduce an undesirable activity.
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Earth's mass has remained constant, and thus the gravitational pull at the surface has decreased over time; Earth's mass has grown with the volume in such a way that the surface gravity has remained constant; Earth's gravity at its surface has increased over time, in line with its hypothesized growing mass and volume.
The American Medical Association was established in D. 1847
