To maintain a uniform spacing between the print media, such as paper, and an inkjet printhead having a large print swath, for instance about 25 millimeters (one inch) wide, a new media support system is provided for inkjet printing mechanisms, such as printers or plotters. The support system employs an endless belt driven from the belt interior surface by a roller drive system that uniformly supports the print media under the reciprocating printhead. The belt may be lined with anti-cockle ribs to support the media when saturated. The belt may also be foraminous, with a vacuum applied thereunder to pull the media onto the belt. A method is also provided for supporting and transporting a large sheet of print media through a printzone of an inkjet printing mechanism, such as an inkjet plotter, that uses such a large swath inkjet printhead.