Why do President Trump and Vice President Biden visit these states so often?

So they can get people to vote for them that's why they go to conventions

Explanation:

the answer is: the sesquicentennial of the american civil war is an occasion to consider the legacy of that great conflict. this legacy is our inheritance, and despite many indelible features, we continue to negotiate the resolution of that conflict. the civil war was fought over slavery, but not always on behalf of slaves

i believe the answer is:

-   william jennings bryan is a democrat while mckinley was a republican

at that time, the segment of population that choose for democratic party were the voters with low economic background and vice versa

- william jennings has support of populists and wants to have inflation to farmers while mckinley has support of bankers and businessmen , doesn't want inflation

the fixed value of gold make the large business able to stack up their gold without   being worried that it would devaluated.

- william jennings supported the silver standard while mckinley supported the gold standard

according to jenning, using other metal beside gold could the poor people to have more purchasing power and them advance in the society.