Joe Belden, 90, a pioneer in public opinion polling and a founder of the nation's first statewide opinion survey, died of Parkinson's disease June 16 at Methodist Home, an assisted living center in Washington.

While working in the late 1930s as a student editor of the Daily Texan at the University of Texas at Austin, Mr. Belden developed an interest in scientific sampling. He took samplings of student opinion on campus and on other campuses nationwide about issues of the day, primarily the possibility of the United States going to war. To learn more about the science of public opinion sampling, he wrote to George Gallup, whose organization responded with detailed instructions on conducting valid public opinion surveys.

Realizing that as a young Mexican American with little experience he would have trouble getting a foot in the doors of potential clients, he organized a sampling of opinion on the 1938 Democratic gubernatorial primary, paid for the polling himself and had the results notarized and sealed. After the election, he took the results to the editor of the state's largest, most influential newspaper, the Dallas Morning News. The editor was impressed with how closely the young Mr. Belden's polling tracked the election results.

The Morning News became the first client of the Texas Poll, which became a model for other regional and statewide surveys. Mr. Belden founded Belden Associates in Austin in 1941, syndicated the Texas Poll and solicited newspapers across the state.

Joseph Belden was born in Eagle Pass, Tex., a small, dusty border town, to parents who were, in the words of Mr. Belden's son, "part of the impoverished Mexican aristocracy." He also was a descendant of Texas independence hero Juan Seguin. He spent his early childhood in Mexico and didn't learn English until he was 9. After graduating from high school in Eagle Pass during the Depression, he borrowed $100 from his former English teacher to pay for his first semester at the University of Texas. He graduated in 1938.

During World War II, he served as a Navy officer in Panama and Washington. After the war, he resumed his survey research business in Austin. He also set up a company in Mexico in 1947 and devised the nation's first radio and television ratings system.

Mr. Belden moved to Dallas in 1952 and expanded into market research, specializing in readership surveys for newspapers across the country. He sold his interest in Belden Associates and retired in 1980. He moved to Washington in 1982.

In retirement, he took up watercolor painting and consulted with a market research firm in Guatemala and with his daughter's Washington-based opinion research firm.

Survivors include his wife of 64 years, Eugenia Belden of Washington; three children, Tom Belden of Merchantville, N.J., Joseph Belden and Nancy Belden, both of Washington; and three grandchildren.

Joe Belden founded the Texas Poll, which became a model for other regional and statewide surveys.