The nation’s most popular summer collegiate baseball league opens its 24th season tonight. The Northwoods League, which features top college players on their summer breaks, has added two expansion teams this year for a total of 20, and nine are in Wisconsin. The Fond du Lac Dock Spiders, owned by the Brewers’ Class “A” affiliate at Appleton, will play their inaugural game in Madison against the Mallards and the Wisconsin Rapids Rafters, who swept the playoffs in four games last year, will start defending their title at home against Kenosha. The Lakeshore Chinooks of Mequon, owned in part by Brewers’ Hall of Famer Robin Yount, open at Battle Creek and the Wisconsin Woodchucks of Wausau are at Green Bay, La Crosse hosts Duluth, and Eau Claire opens at the other expansion home in Bismarck, North Dakota. More than one-point-one million fans attended Northwoods League games last year.