7. what were the greatest problem facing urban areas in the late 20th century? explain.
· overcrowding
· sanitation
· crime
8. who was the most influential muckraker? explain.
· jacob riis
· ida tarbell
· upton sinclair
· lincoln steffens
· john spargo
9. who was the most successful progressive era president? explain.
· theodore roosevelt
· william h. taft
· woodrow wilson

  7• Sanitation

Explanation:     In the late 1800s, people living in American urban areas confronted various issues in their homes and in their working environments. Poor sanitation and no channeled water have been the major problem among them. There was no funneled water until 1948; thus, sanitation was poor. This implied frequencies of infections, for example, cholera were high among the populace in urban areas. This exacerbated by the expanding the greatest problem facing by urban areas in the late 20th century.  

  8• Jacob Riis  

Explanation:    Jacob Riis is the best-known about the purported Muckrakers, Muckrakers were columnists and analytical correspondents who expounded on corruption and injustice somewhere in the range of 1890 and 1920. He is a crusading writer dynamic from around 1890 to 1920 (and sometimes, numerous years longer) who realized various legislative changes and to feature the debasement of government officials and well off representatives.  

  9• Theodore Roosevelt

Explanation:   Theodore Roosevelt (1858–1919) was the best Progressive Era 26th President of the United States (1901–1909) and furthermore filled in as Governor of New York and Vice President. He is known for turning into the main representative for his adaptation of progressivism after 1890. His organizations saw an extraordinary social and political change in American culture. As an individual from the Republican Party, Roosevelt had filled in as President from 1901 to 1909, ending up progressively dynamic in the later long stretches of his administration.  

the underground railroad (apocope of the metropolitan railroad) is a system of urban trains located within a city and its metropolitan area. it is characterized for being a massive transport of passengers in the big cities, uniting diverse zones and their environs, with high capacity and frequency and in segregated form to other systems of transport. metropolitan railroads are built underground or on the surface, although most systems use mixed models where sections are combined in both modalities.

1 - as a result, the metro tends to reduce car travel for two reasons: first, due to the greater transfer of users from the car and, second, due to the reduction in the acquisition of cars in homes located in sectors near the stations of the metro.

2 -the metro allows to contribute effectively to the achievement of all the objectives of an urban development policy: it improves the efficiency of the city's economy by reducing travel costs and also generates a higher level of activities in the city center, taking advantage of of the agglomeration economies.

3 -it is a clean means of transport, since it uses renewable energy (usually electricity), taking care of the environment and avoiding excessive pollution.