Secunda Classis - Roma Aeterna XLIV Lines 318–320

Secunda classis intrā centum ūsque ad quīnque et septuāgintā mīlium cēnsum īnstitūta est…

The translation I have reads, “The second class was drawn up out of those whose rating was between a hundred thousand and seventy-five thousand;”

My question is about the word cēnsum. Why is it accusative? It seems that an ablative would make more sense here. I also realize that cēnsum may be a genitive plural. Would it then be genitive of the whole?

Both intra and ad are prepositions with the accusative, hence censum



Secunda classis īnstitūta est intrā cēnsum centum mīlium ūsque ad cēnsum quīnque et septuāgintā mīlium …