April 2010 marked a milestone for Art Chicago.

It was the 30th anniversary of Chicago's first international art fair, dubbed the Chicago International Art Exposition and staged on Navy Pier in May 1980. In the three decades since, the fair changed hands (and names) a half-dozen times, ultimately landing in the lap of corporate art fair giants Merchandise Mart Properties Inc., which saved the previously independent fair from certain bankruptcy in 2006 and has produced it at the Merchandise Mart ever since.

Thirty-one years, on the other hand, is different.

Five years into MMPI's version of Art Chicago, locals have learned to associate the fair with the Artropolis moniker, coined by MMPI as an all-inclusive umbrella under which the traditional Art Chicago fest lives alongside the contemporary-driven NEXT exhibition of emerging art, now in its fourth year, and the International Antiques Fair, which MMPI has hosted since 1997. Together under the same massive roof, the trio of fairs coexist as a one-stop Midwestern shop for international collectors who may very well be shopping for art and furniture in the same way they pick out matching cabinetry and counters elsewhere in the building.

This year, the lines between MMPI's fairs will blur even further: Art Chicago and NEXT share a floor in the Mart (they've previously been on separate floors), feasibly making it easier for collectors to roam from classic to contemporary. According to MMPI vice president Paul Morris, who is Art Chicago's acting director, the combined floor plan came by request.

"We were encouraged by both collectors and dealers, making it easy for collectors as possible to navigate the fair," Morris said last week, adding that visitors will be able to cross back and forth between established work and emerging work, as opposed to waiting in line for the Mart's elevators.

NEXT curatorial director Ken Tyburski maintained that despite this year's comingled floor plan, the number of exhibiting galleries will remain roughly the same as last year, and the "energy is going to be that much greater" with the two fairs combined.