Walk through the Fourth Avenue entrance to the Central Library and you will see a simple wooden box. It's black, 14 inches by 7 inches, and sits by the security desk.
If your bag doesn't fit into the box, you can't bring it into the library, much like the requirements for carrying luggage onto a plane.
Because it keeps big bags out of the library, the library's black box also keeps some homeless people out, since many are loathe to leave all they own outside on the sidewalk.
The box has been there since the Rem Koolhass-designed building of steel and glass opened in 2004.
But lately, some homeless people say, library staff have stepped up enforcement of the rule on bag size.
"I personally have been discriminated against, gotten suspicious looks and treated poorly because I often carry a suitcase bag that causes me to appear homeless," said a Seattle resident and library patron who wishes not to be named. "It's only gotten worse, since the homeless problem has increased."
Andra Addison, spokesperson for Seattle Public Library, said in an email to Real Change that the box helps enforce the bag-size policy.
"It ensures aisles are clear and that our buildings can be safely and quickly evacuated in an emergency," she said.
Addison said the rule is not meant to discriminate against the homeless. "It is an important rule to ensure the safety and accessibility of Library spaces for all our patrons, including the homeless."
Unlike the airlines, Seattle Public Library does not limit the number of articles you can bring into the library. They just need to meet the size requirement, Addison said.