Please Help and look at my other questions : Who was responsible for selling/trading slaves to Europeans?

Explanation:

The Atlantic slave trade, transatlantic slave trade, or Euro-American slave trade involved the transportation by slave traders of enslaved African people, mainly to the Americas. The slave trade regularly used the triangular trade route and its Middle Passage, and existed from the 16th to the 19th centuries

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.

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.