What is the leading theory about how early humans arrived on the american continents?

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.

the united states constitution defines the structure of the national government and dictates the scope and limitation of its powers. the constitution is known as “the supreme law of the land” and all other laws are measured against it. the application of the articles and amendments of the constitution comprise constitutional law.

in addition to the united states constitution, each state has its own constitution and therefore, its own body of constitutional law as well. state constitutions resemble the federal constitution in that they outline the state government’s structure of legislative, executive and judicial branches as well as contain a bill of rights.

but there are various ways state constitutions differ from the federal constitution. often, state constitutions are much longer and more detailed than the federal constitution. state constitutions focus more on limiting rather than granting power since its general authority has already been established. as a result, the constitution of alabama is six hundred pages long whereas the federal constitution can be easily read in one sitting front to back.

the details in state constitutions are not particularly “constitutional” in nature. they often address topics unique to the state. the federal constitution can only be amended through a lengthy process designed to limit changes to this fundamental document. as a result, it has only been amended seventeen times since the adoption of the bill of rights in 1791.

state constitutions are more open to amendments. amendments can be proposed by legislature, a constitutional commission or citizens’ petition and can be accepted by referendum.   for example. the constitution of massachusetts has been amended one hundred and twenty times. the constitution of georgia has even been replaced altogether as many as ten times.