(Undated)  --  Portland's park system is ranked among the nation's best.  The Trust for Public Land gives Portland a score of four-point-five out of a possible five, good enough to be tied with New York City for fifth place.  Factors considered in compiling the rankings include park access, park facilities, distance to parks, and median park size.  Minneapolis and St. Paul are tied for first place in the park-system survey, followed by Washington, D.C. and San Francisco.