>>> WE'RE BACK WITH A CRISIS AT THE BORDER. A RECORD 12,000 UNDOCUMENTED MIGRANTS STOPPED IN A SINGLE DAY BY BORDER PATROL THIS WEEK. AND AS JULIA AINSLEY REPORTS, IT'S ADDING UP TO MORE STRAIN ON SOME OF AMERICA'S BIGGEST CITIES. >> Reporter: TONIGHT, DENVER JOINING THE GROWING LIST OF CITIES STRUGGLING TO HANDLE A RECORD SURGE OF MIGRANTS, WITH ENTIRE BLOCKS FULL OF MIGRANTS SLEEPING ON THE STREET. >> OH, IT IS A CRISIS. >> Reporter: MIKE JOHNSTON IS ONE OF FIVE DEMOCRATIC MAYORS RECENTLY WRITING PRESIDENT BIDEN, SAYING ACTION IS NEEDED TO HELP CITIES ADDRESS THE CRISIS. WHAT'S THE ONE THING YOU WANT FROM THE BIDEN ADMINISTRATION RIGHT NOW? >> WHEN YOU ADMIT SOMEONE FOR ASYLUM IN THIS COUNTRY, THEY SHOULD GET WORK AUTHORIZATION. WE SHOULD EXPEDITE THE PROCESS OF APPROVING THAT APPLICATION SO IT DOESN'T TAKE FOUR YEARS, IT COULD TAKE 30 DAYS. >> Reporter: JOHNSON IS UNDER INCREASING PRESSURE FROM COUNTIES OUTSIDE OF DENVER THAT ARE NOT TAKING IN MIGRANTS. SUBURBAN DOUGLAS COUNTY PASSING A RESOLUTION DEMANDING DENVER DROP ITS STATUS AS A SANCTUARY CITY, A JURISDICTION WHERE OFFICIALS WON'T ENFORCE FEDERAL IMMIGRATION LAWS. CRITICS SAY THAT ATTRACTS MORE MIGRANTS WITH ILLEGAL CROSSINGS AT THE SOUTHERN BOARD ER THIS YEAR AT RECORD HIGHS. WHAT WOULD YOU LIKE TO SEE THIS CITY DO? >> I'D LIKE THE CITY TO ACTIVELY PROCLAIM THAT IT NOT A SANCTUARY CITY. I THINK IT'S IMPORTANT THAT WE'RE NOT BRINGING PEOPLE TO A COLD WEATHER CLIMATE. >> Reporter: THERE ARE MORE THAN 2600 MIGRANTS IN DENVER SHELTER SYSTEMS, AND NOW NEARLY 30,000 WHO HAVE COME THROUGH DENVER IN THE LAST YEAR, COSTING TAXPAYERS MORE THAN $32 MILLION SO FAR. DENVER SHELTERS ARE FULL, WITH SOME MIGRANTS NOW SLEEPING IN TENT ENCAMPMENTS LIKE THESE, WHERE TEMPERATURES DROP BELOW FREEZING AT NIGHT. >> IT JUST SEEMS LIKE PRETTY INCONVENIENT FOR THEM AND FOR US. REALLY, A LOT OF PEOPLE IN THIS APARTMENT COMPLEX ARE CONCERNED. >> Reporter: FAMILIES WITH CHILDREN ARE GIVEN PRIORITY IN DENVER SHELTERS. WE MEET A GROUP OF ADULTS WHO JUST ARRIVED. GENESIS FROM VENEZUELA SAYS THEY DON'T KNOW WHERE THEY'RE SUPPOSED TO GO NEXT. "WE DON'T KNOW. WE HAVE NO KNOWLEDGE, DIRECTION, LOCATION," SHE IS SAYING. JAN SAYING WE HAD TO GO THROUGH SEVEN COUNTRIES ON FOOT, THROUGH THE JUNGLE. WE CAME FOR THE OPPORTUNITY, FOR T