The Washington State Convention Center is a convention center located next to and over Interstate 5 in downtown Seattle, Washington, adjacent to Freeway Park. Planning for its construction began in 1982; construction began in 1985, and the center opened on June 18, 1988. An expansion that doubled the usable space was undertaken from 1999 to 2001, designed by LMN Architects of Seattle. It has 307,700 square feet (28,590 m) of total meeting space. The convention center averages over 400,000 visitors a year. A $766 million proposed expansion, to be completed by 2014, would double exhibit space.