Which was the main issue that divided presidential candidates of the democratic and republican parties in the late nineteenth century?

In the late 19th century after the Civil War, the Republican Party dominated most of the elections, since Abraham Lincoln (1860) all the way to Franklin Roosevelt (1933).

The major political issues during this period were tariff, currency reform and civil service reform.  

The Republican Party had been firmly established as the party of big business while the Democratic Party was the party of agriculture and values.

The Election of 1896 between William McKinley (Republican) and William Jennings Bryan (Democrat) was the most important sine the election of 1860. The Republicans appealed to the propertied classes while the Democrats appealed to the farmers.

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.

“i think it is very plausible that if there are five votes to end the death penalty, it could be with the people who are on the court right now,” - smith

so basically it is not clearly and consistently imposed