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It's no secret that for most retirees, Social Security is an important part of their income. Exactly how much varies from individual to individual — and, apparently, from city to city. Among 100 U.S. cities with the largest 65-and-older populations, Social Security makes up an average 42 percent of retiree income, according to recent research by SmartAsset.com. The range is from more than 53 percent to about 27 percent. The research evaluated retiree income from both Social Security and other sources — i.e., pension plans, annuities, individual retirement plans — using government data. The analysis excluded work-related income, which a growing number of older Americans are using to supplement their cash flow.

The research shows that places where Social Security makes up the largest income piece tend to be lower-cost areas — including some in states where income (or, specifically, Social Security income) doesn't get taxed. The cities where it's a smaller portion of retiree income tend to have a higher cost of living and higher incomes among its residents. For people still in their working years, the research should point to the importance of setting aside savings now to provide you with income in your later years when full-time work is behind you. In other words, Social Security will only go so far.

Where retirees rely on Social Security the most Rank City Average Social Security income Average other retirement income* Average combined income* Social Security as a share of overall retirement income* 1 Fort Wayne, Indiana $21,247 $18,266 $39,513 53.8% 2 Hialeah, Florida $13,858 $12,009 $25,867 53.6% 3 Wichita, Kansas $21,034 $20,649 $41,683 50.5% 4 Sun City, Arizona $21,187 $20,994 $42,181 50.2% 5 Indianapolis, Indiana $20,115 $20,362 $40,477 49.7% 6 Lincoln, Nebraska $21,602 $22,262 $43,864 49.3% 7 Toledo, Ohio $18,109 $19,142 $37,251 48.6% 8 Tulsa, Oklahoma $20,377 $21,889 $42,266 48.2% 9 Milwaukee, Wisconsin $18,356 $19,743 $38,099 48.2% 10 Port St. Lucie, Florida $21,579 $23,282 $44,861 48.1%

"Sometimes the numbers look too big and scary so you don't want to think about it," said AJ Smith, vice president of financial education at SmartAsset. "Instead, think about the options you have available and take advantage of what you can do now." For example, if you have access to a 401(k) plan or similar tax-advantaged retirement-savings account through work, experts typically recommend putting in enough to get any matching company contribution.