Families with kids made 1 billion fewer visits to U.S. restaurants over the past six years.

Sandwiches are the cornerstone of lunch and dinner menus at both limited- and full-service restaurants, where they are offered more than any other entree.

A new national study of eating out and income shows that fast-food dining becomes more common as earnings increase from low to middle incomes, weakening the popular notion that fast-food should be blamed for higher rates of obesity among the poor.