Absolutely made in Chicago. A few of the 10-speeds that year were made in Taiwan or Japan... LeTour's and so on built by Panasonic. Everything else was Chicago built.
Your 1977 should have an "N" for the second digit in the serial number. There should be a corresponding date stamped in tiny numbers on the headbadge. First three digits of that number would be the day, and 4th digit is the year (7).