Why has American work ethic been seen as a key ingredient top our economic success?

Convinced that selfreliance, the work ethic, and aggressive individualism forged in the crucible of America's frontier experience had been key ingredients in the ... what would sustain such traits in a 20th-century world marked by the growth of ... industrial labor, their presence was essential to the country's rapid economic .

Explanation:

the  wilmot proviso  was designed to eliminate  slavery  within the  landacquired as a result of the mexican war (1846-48). fearing the addition of a pro-slave territory, pennsylvania congressman david  wilmot proposedhis amendment to the bill.