Which statement best describes urban areas during the late 1800s?
Urban areas were often sparsely populated with few employment opportunities.
Many cities were overcrowded with limited housing and few sanitation services.
Urban areas were designed to encourage people to commute to work and live in suburbs.
Many cities were often free of political corruption with few limitations on who could vote.

Between 1880 and 1900, cities in the United States grew at a dramatic rate. Owing most of their population growth to the expansion of industry, U.S. cities grew by about 15 million people in the two decades before 1900. Many of those who helped account for the population growth of cities were immigrants arriving from around the world. A steady stream of people from rural America also migrated to the cities during this period. Between 1880 and 1890, almost 40 percent of the townships in the United States lost population because of migration.

Industrial expansion and population growth radically changed the face of the nation's cities. Noise, traffic jams, slums, air pollution, and sanitation and health problems became commonplace. Mass transit, in the form of trolleys, cable cars, and subways, was built, and skyscrapers began to dominate city skylines. New communities, known as suburbs, began to be built just beyond the city. Commuters, those who lived in the suburbs and traveled in and out of the city for work, began to increase in number.

Many of those who resided in the city lived in rental apartments or tenement housing. Neighborhoods, especially for immigrant populations, were often the center of community life. In the enclave neighborhoods, many immigrant groups attempted to hold onto and practice precious customs and traditions. Even today, many neighborhoods or sections of some of the great cities in the United States reflect those ethnic heritages.

During the final years of the 1800s, industrial cities, with all the problems brought on by rapid population growth and lack of infrastructure to support the growth, occupied a special place in U.S. history. For all the problems, and there were many, the cities promoted a special bond between people and laid the foundation for the multiethnic, multicultural society that we cherish today.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.