In spite of the risks of causal dining and fast-food restaurants, the mid-20th century provided many new opportunities for creative menu design. By the end of the 1960s, the increasingly popular coffee shops and restaurants that featured a singular item such as pizza, steak, or pancakes used new menu graphics. The 1970s brought a decline in eating out, but the 1980s, especially in homes where both parents were working, brought a big increase in the demand for many types of restaurants. Since then, menu design has provided the American public with a pleasing prelude to the dining experience. Some popular historians are studying menus as a very special kind of documentation of America's love of eating out. For many generations of diners, taking a restaurant menu has been a way of preserving a memory or documenting a trip or a voyage. Many restaurants have provided customers with souvenir versions of their menus. The restaurants owners believe that this is a good way of advertising. Thus the menu now serves a new, but also important function.