Check some reasons why Americans have regional dialects.

migration patterns from England
geographic barriers cause variations
economic conditions help to cause various dialects
influence of other languages

Some reasons why Americans have regional dialects are geographic barriers that cause variations and the influence of other languages.

Explanation:

English is the most widely spoken language in the United States, and its de facto official language. But being such a vast country, this language has regional variations, called accents or dialects, that make a person from the same country speak in a very different way depending on the region in which they live.

Mainly two factors contribute to this variability of the language: on the one hand, the different geographical and geological barriers create differences between the different sociocultural groups of regions separated from each other. A clear example is the dialect of the northern United States, which in turn has variations between the Boston, New York, and Midwest accents. Specifically, the variations between the Midwest accent and that of New York is given by the distance between both regions, exacerbated by the presence of the Great Lakes, which divide the north of the country into two different cultural regions, thus changing the accent due to geographical isolation at the time of birth of both dialects.

On the other hand, the influence of immigration and the languages that immigrants bring with them, as well as the influence of the languages of neighboring countries, determine the accents of a certain region. For example, the Miami accent is a typical Latin accent, strongly influenced by Latin American migration flows in the area. On the other hand, the Boston accent has great legacies from the accent of the first settlers of the nation, that came from England. Another clear example is the New Jersey accent, whose Italian influence is undeniable.

they required less loading and unloading

explanation:

the shipping container improved shipping because it cut down on unloading time by three weeks, eliminated wasted space, and allowed ships to carry.