Why Pandas?
#pass all lines untils 'fips txt' with open('input_file.txt, 'r') as in_file: while in_file.readline().split()[0] != 'fips': pass # write the rest in separed files for line in in_file.readline(): with open('{}.txt'.format(line.slit()[0]), 'w') as out_file: out_file.write(line)