Parse a csv file and create a dictionary of partial results
You're on the right track, using a with block to open the file and csv.DictReader() to parse it.

Your list handling is a bit clumsy, though.  To skip a line, use next(f).  Avoid making a list of the entire file's data, if you can process the file line by line.  The dict comprehension has an unnecessary complication as well.

with open('file.csv') as f:
    _ = next(f)
    reader = csv.DictReader(f)
    counties = { line['County']: line['State'] for line in reader }


Your sample file had County as the header, whereas your code looked for line[‘county’].  I assume that the curly quotes are an artifact of copy-pasting, but you should pay attention to the capitalization.