The PROKOP family I'm tracing may not be related to you at all, but because one source suggests that the name was Anglicized I am playing a long shot.
The 1900 census for Lincoln Co., Oklahoma Territory states that Joseph PROKOP was born in Bohemia, date unknown.Anna, his wife, was born in Iowa in 1854.Her parents were born in Bohemia -- but I don't know their names. Joseph and Anna were married in 1886, most likely in either Iowa or Nebraska.
I have not been able to link Joseph PROKOP with other Bohemian families in the area and the sparsity of information about him makes me question even his birthplace.
There is slight, completely circumstantial, evidence that could link this family to Hungary.
Food for thought:might our Jospeh PROKOP have belonged to a branch of your family that came to this country much earlier?