Williams is pretty confident about that claim, he's been collecting posters for 40 years.
"I buy something almost everyday," Williams said.
The result is more than 200,000 posters housed in his TriBeCa store.
When you step inside, the colors, the subjects, and the piles alone can overwhelm a new collector.
"If we can get an idea of a size or subject we can find what it is they are interested in," Williams said.
The posters range in themes from movies, travel, food, Liquor, politics and even propaganda.
How about posters to encourage buying bonds after World War I?
"The colors, the sense of hope, the fresh beginning," Williams said.
Until 1880, posters were printed in black and white, but with the addition of color, posters came to life, as did the subjects they were advertising.
"The French probably produced the most and the best posters," Williams said.
The ones that end there or in other collections are usually posters that were never actually pasted on public walls.
They may have been extra prints that were set aside.
That means they are usually in good condition, though minor rips and tears can sometimes be fixed.
To help keep the posters in good shape, they are mounted onto canvas.
Some like an old ad for milk will set you back a bit.
But fortunately, you can enter the poster market for under $100.
"There's a wide rage that can fit any pocketbook," Williams said.
If you'd like to check out the shop or the collection visit www.postermuseum.com.