WILL RECEIVE PRIORITY.

>>> TOMORROW IS AN IMPORTANT CIVIC DAY FOR MORE THAN ONE REASON.

APRIL 4 IS ALSO AN ANNUAL CITY HOLIDAY OF SORTS.

IT IS CHICAGO FLAG DAY.

WE HAVE THE STORY OF A HOMEGROWN COMPANY THAT MAKES FLAGS AS THEIR BUSINESS.

>> Reporter: WENT TO CHICAGO AND HERE'S THE LETTERS WGN, THEY THINK OF THE BROADCASTING STATION.

>> WE WERE ALONG THE HERE , WE WERE HERE LONG BEFORE TV.

I LOVE THEM, BUT WE WERE HERE FIRST.

>> WGN STANDS FOR --.

>> THE COMPANY STARTED BY MY GREAT-GRANDFATHER PURCHASING A STICK FLAG FROM A STREET MERCHANT, WALKING DOWN THE STREET AND SELLING IT FOR TWICE WHAT HE PAID FOR IT.

>> Reporter: 108 YEARS LATER, THE FLAG COMPANY IS STILL SOARING.

FOR OVER A CENTURY, IT HAS BEEN DONE IN THE SAME BUILDING.

THIS SEAMSTRESS HAS BECOME A FLAG MAKING PRO.

>> IT WILL BE 37 YEARS.

>> 37 HERE'S GOING COULD YOU DO THIS NOW IN YOUR SLEEP?

>> YEAH .

[ LAUGHTER ] >> Reporter: GETTING THE FLAGS MADE FOR THE BLACKHAWKS IS STILL DIFFICULT.

>> WE HAVE DONE ALL THE CHAMPIONSHIP BANNERS.

EVERY DYNASTY IN CHICAGO ENDS UP COMING BACK HERE.

>> Reporter: PICK A HALLMARK EVENT, CHANCES ARE , WGN HAS MADE A FLAG OR BANNER FOR IT.

V-J DAY, THE PASSING OF POLITICIANS.

>> MY FATHER GOT A CALL THANKSGIVING MORNING AND HAD TO LEAVE THINGS GIVING DINNER TO COME DOWNTOWN AND START PUTTING DRAPES UP THROUGHOUT THE CITY.

>> Reporter: AND QUEEN ELIZABETH'S HISTORIC VISIT.

>> IF HE CAN BE THE SAUSAGE KING OF CHICAGO, I CAN BE THE FLAG KING OF CHICAGO.

>> Reporter: CHICAGO FLAG DAY MARKED THE DATE IN 1917, ONE YEAR AFTER WGN'S FOUNDING, THAT THE CITY COUNCIL ADOPTED THE NOW ICONIC CHICAGO FLAG.

'S, YOU CAN GO INTO ANY CORNER OF THE COUNTRY AND THE FLAG WILL STILL BE RECOGNIZED PEOPLE ARE GOING TO KNOW WHAT IT IS.

THAT IT MEANS THESE GUYS MUST BE CHICAGOANS.

>> Reporter: THE DESIGN IS SO SIMPLE AND YET EVERY ELEMENT HAS MEANING >> POP QUIZ, CAN YOU DO IT?

>> I THINK I CAN.

WE HAVE FORT DEARBORN, THE FIRST ARE.

THE SECOND START IS GOING TO BE THE GREAT CHICAGO FIRE.

THEN WE HAVE THE COLUMBIAN EXPOSITION, THEN THE CENTURY OF PROGRESS.

THAT IS THE ONE EVERYONE FORGETS.

>> THERE HAS BEEN TALK ABOUT ADDING A FIFTH ARE.

IN 1976 IS GREAT-GRANDFATHER OVERHEARD THOSE TALKING ABOUT HONORING A FORMER MAYOR.

A COMPANY HAS A FEW OF THE VINTAGE FIVE STARS LEFT.

WGN AND FLAG COMPANY KNOWS ABOUT DURABILITY AND SURVIVAL.

>> PEOPLE ABSORB IT.

IT BECOMES PART OF THEIR SOUL.

THE CITY OF CHICAGO STARS & STRIPES, TO SOME PEOPLE, THAT IS THEIR LIFE.

THERE ARE PEOPLE WITH THAT TATTOOED ON THEM.

WHILE I DO NOT HAVE THAT TATTOOED ON MYSELF, I CAN'T SAY I BLAME THEM.

>> CERTAINLY NO FLAG LIKE IT ONE OF THE BEST IN THE WORLD, IF I DO SAY SO MYSELF I WILL NOT GET A TATTOO.

>> IF YOU WANT A FLAG OF YOUR OWN, WGN CAN PRODUCE NEAR ANY VARIATION.

THE COMPANY HAS SWAPPED THE CHICAGO STARS FOR