Which us state was once its own kingdom ?

Hawaii was once its own kingdom and later constituted as state

Explanation:

Hawaii is also called a big island; it was ruled by King Kamehameha from 1810 to 1893. It was an independent kingdom until 1893 and it called itself a republic in the year 1894.

King David Kalakaua was the last ruler of Hawaii. The kingdom was removed from power by businessmen and mainly sugarcane cultivators who have asked the Queen Liliuokalani to step down. Finally, in the year 1898, it was annexed with the USA has the 50th state in the union.

b) race riots in several cities

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.