Why did cities grow during the gilded age

Between two great wars - the Civil War and the First World War - the United States of America came of age. In a period of less than 50 years it was transformed from a rural republic to an urban nation. The frontier vanished. Great factories and steel mills, transcontinental railroad lines, flourishing cities, and vast agricultural holdings marked the land. With this economic growth and affluence came corresponding problems. Nationwide, a few businesses came to dominate whole industries, either independently or in combination with others. Working conditions were often poor. Cities grew so quickly they could not properly house or govern their growing populations.