The CTA maps commuters rely on to get around are disappearing at a high rate -- along with your tax dollars.



The maps are popular targets for college students to steal and display in their dorm rooms.



Students at a number of Chicago-area schools, including DePaul, Columbia and Northwestern are fans of the trend of adorning their walls with the maps, NBC 5 Investigates learned.



Thieves will even boast on social media about pilfering maps.



So how much does it cost the CTA?



Over the last two years, the agency has spent more than $216,000 to buy more than 85,000 maps -- an average of 71 maps for every rail car in the system.



"It's great that these customers are really fans of the CTA and want to have a piece of it," CTA Vice President of Communications and Marketing Brian Steele said. "The unfortunate part is what they're doing is illegal."



Steele says the numbers do not reflect the true losses the CTA faces due to the decoration of dorm rooms.



"The replacements we've been doing for rail maps overwhelmingly have been related to the project and new stations that we've opened in the last two years, and have not been related to any thefts," Steele said.



Last year, DePaul raided dorm rooms on their campus and confiscated more than 150 maps. But Steele says only about 50 could be reused.



So why not make the maps harder to steal by putting a protective cover over them? CTA officials say they intentionally keep them easy to swap out in order to make that process quick and cost-effective.



More rail cars are being equipped with cameras, and officials believe that may be the best way to catch the thieves.