city park of designed following the principles of Frederick Law Olmsted, who is most famous for designing New York City's Central Park, is comparably diverse and ornate. The city's economic base is also diverse, featuring Massachusetts's wealthiest Fortune 100 company, MassMutual Insurance, as well as numerous universities and hospitals. Springfield features thousands of Victorian era Painted Lady mansions (like San Francisco's), e.g., in the McKnight Historic District. In addition to the Connecticut River, Springfield features Watershops Pond, Porter Lake, and the Mill River. Less than two miles south of Springfield, Six Flags New England amusement park is located in suburban Agawam; and one mile west of Springfield, The Big E—the collective state fairgrounds of all six New England States—is located in West Springfield. North of Springfield, the U.S. Westover Air Force Base is located in the resurgent, former industrial city of Chicopee. The City of Chicopee features the confluence of the fast-moving Chicopee River and the meandering Connecticut River. The Chicopee River, although only 18.0 miles long, has the largest water basin in Massachusetts—and along the Connecticut River—at 741 square miles. Across from Chicopee, on the west side of the Connecticut River, the Holyoke Mall at Ingleside is one of the largest malls in New England. In addition to the mall, Holyoke is home to the Mount Tom Range of mountains, the Holyoke Canal System, and the Volleyball Hall of Fame. (The sport of volleyball was invented in Holyoke in 1895.) The city of Westfield features Westfield State University, founded by renowned education reformer Horace Mann. Near to Westfield—approximately 15 miles west of Springfield—numerous outdoor opportunities are available, such as alpine skiing at Blandford Ski Area and the United States's oldest white-water rafting races on the 78.1 mile Westfield River, the longest Connecticut River tributary in Massachusetts. The international airport that serves Hampden County, and the Pioneer Valley in general, is Bradley International Airport, which is located 12 miles south of Springfield in the town of Windsor Locks, Connecticut, land that formerly belonged to Springfield. Demographics Ethnicity Currently, the Pioneer Valley's ethnic and racial diversity varies greatly from city to town. Predominantly British until the 19th Century, and then European-American in the late 19th and 20th centuries, as of the 2010 Census, the region features a rapidly growing Hispanic population in nearly all urban areas. This influx includes large numbers of Puerto Ricans. Among the European-American community, the Pioneer Valley's