Final answer:
Maycomb remained unchanged in size due to its distance from industrialization and modern transportation routes, which were critical for urban growth in nineteenth-century America. The contrast with industrial towns like Coketown highlights the significance of transportation and industrial infrastructure in urban expansion.
Step-by-step explanation:
The town of Maycomb remained the same size largely because it was far from major transportation routes and hubs of the industrial revolution. In the late nineteenth-century America, massive urban growth was driven by several essential elements: proximity to transportation like rivers and railroads, the concentration of factories and industries, and the migration of people seeking employment opportunities. Without these, towns like Maycomb were left untouched by the explosive development seen elsewhere.
The idiosyncrasy of Coketown, heavily characterized by smoke and industry, contrasts sharply with the static nature of Maycomb. Coketown's description paints a picture of an urban, industrialized environment with all the infrastructure leading to growth: smoke from iron-foundries, wharves, trains, and smoke-covered everything is indicative of the industrial activity that powers urban expansion. Meanwhile, Maycomb's stagnant size suggests a lack of these growth-promoting factors, especially modern transportation and industry.
Ultimately, it was the growth of the suburbs and middle-class migration that characterized the shift in population centers, leaving behind rural towns like Maycomb which lay untouched by the industrialization and therefore remained static in their development.