People from all three eastern regions (new england, southeastern, midlands) migrated into the midwest, great plains and western united states. why is there a relatively uniform form of english (dialect) spoken across this enormous area?

When lawrence saw the posters for the circus hanging on the bulletin board, as he swept up the trimmings at slim's barbershop, he knew he would be taking his little cousins. they loved animals, and he was looking forward to seeing the smiles on their faces as the circus performers amazed them with their stunts. but sweeping up hair clippings didn't pay a whole lot. lawrence spent 45 dollars just getting tickets. but it was worth it to see his cousins' faces. the day finally came and everyone was excited as they walked into that big circus tent. but lawrence soon realized that he and his cousins would be thirsty and hungry. as they sat in their seats, the drink vendor walked by selling beverages. desperately thirsty, lawrence asked him how much a lemonade would cost, and the drink vendor said, "eleven dollars each." lawrence replied, "oh, that's it? just eleven dollars? what a great deal for one cup of lemonade. that's totally worth it." the drink vendor walked away. which type of irony is used?

He leaned his head against the wall; his eyes were shut, his hands clasped in each other, and his body seemed to be sustained in an upright position merely by the cellar-door against which he rested his left shoulder. the lethargy into which he was sunk seemed scarcely interrupted by my feeling his hand and his forehead. his throbbing temples and burning skin indicated a fever . . there was only one circumstance that hindered me from forming an immediate determination in what manner this person should be treated. my family consisted of my wife and a young child. our servant-maid had been seized, three days before, by the reigning malady, and, at her own request, had been conveyed to the hospital. we ourselves enjoyed good health, and were hopeful of escaping with our lives. our measures for this end had been cautiously taken and carefully adhered to. they did not consist in avoiding the receptacles of infection, for my office required me to go daily into the midst of them; nor in filling the house with the exhalations of gunpowder, vinegar, or tar. they consisted in cleanliness, reasonable exercise, and wholesome diet. who is the story’s first-person narrator

How did the man from "to build a fire" put his life in danger?