The Census Bureau reports that, despite rising gasoline prices, use of public transportaion in commuting to work declined between 1970 and 1977 in most of 20 cities it studied. Overall, the bureau says, the study of 20 metropolitan areas indicates 7.3 percent of people commuting to work used public transportation in 1977. The 1970 census had shown 10.3 percent of commuters using public transport. The biggest decline was recorded in Newark, N.J., where use of public transit dropped from 20.3 percent to 12.5 percent of commuters during the seven years, the report said. By contrast, among the cities studied, increases in public transit use were reported in Salt Lake City, Utah, and Anaheim-Santa Ana-Garden Grove, Calif. However, the overwhelming majority of workers continue to commute by auto or truck, with some 91 percent in this category. Of the total, 72 percent rode alone in a car or truck, while the remainder either carpooled or rode with someone. The median distance to work in the cities surveyed was 7.7 miles, the bureau said, and median travel time was about 20 minutes by auto and 33 minutes by public transit. Among the cities, Saginaw has the highest percentage of commuters driving alone to work, 82 percent. The lowest percentages were in Washington, D.C., 58 percent, and Boston, 59 percent. The Washington area had the highest carpooling rate, at 25 percent, but transit use here declined 3.2 percent. Here is a list of the 20 metropolitan areas studied, the percentage of workers in each driving alone to work and using public transit in 1977 and the percent change in public transit use since 1970 (the totals will not be 100 percent because of other forms of transport, such as carpooling, walking, bicycles and so forth): Boston, 59 percent drive alone and 19 percent use public transit, down 3.5 percent; Newark, 69 percent drive alone and 13 percent use public transit, down 7.8 percent; Anaheim-Santa Ana-Garden Grove, 79 percent drive alone and 2 percent use public transit, up 1.5 percent; Detroit, 78 percent drive alone and 4 percent use public transit, down 4.5 percent; Los Angeles-Long Beach, 76 percent drive alone and 5 percent use public transit, down 0.7 percent; Pittsburgh, 68 percent drive alone and 13 percent use public transit, down 3.1 percent; Washington, 58 percent drive alone and 15 percent use public transit, down 3.2 percent; Albany-Schenectady-Troy, 70 percent drive alone and 6 percent use public transit, down 3.1 percent; Minneapolis-St. Paul, 70 percent drive alone and 3 percent use public transit, down 1.1 percent; Dallas, 77 percent drive alone and 3 percent use public transit, down 3.6 percent; Fort Worth, 77 percent drive alone and 2 percent use public transit, down 1.1 percent; Memphis, 74 percent drive alone and 5 percent use public transit, down 6.3 percent; Tacoma, 77 percent drive alone and 2 percent use public transit, down 1.5 percent; Madison, 66 percent drive alone and 9 percent use public transit, up 0.7 percent; Orlando, 76 percent drive alone and 2 percent use public transit, down 1.9 percent; Phoenix, 79 percent drive alone and 1 percent use public transit, down 0.6 percent; Saginaw, 82 percent drive alone and less than 1 percent use public transit, down 1.2 percent; Salt Lake City, 71 percent drive alone and 6 percent use public transit, up 3.6 percent; Spokane, 76 percent drive alone and 4 percent use public transit, down 1 percent; Wichita, 78 percent drive alone and 2 percent use public transit, down 0.8 percent.