WASHINGTON -- For the first time, the Census Bureau is giving U.S. households a chance to respond to government surveys over the Internet to save costs and boost sagging response rates in a digital age.

The online option will supplement the traditional mail-out operation. The agency has relied almost exclusively on paper forms since 1970. It is moving now toward a more Internet-based system after spending a record $13 billion on the 2010 census.

"The Census Bureau is transforming to make responding to surveys more convenient, conducting surveys more cost-effective and America's statistics more accessible on digital and mobile devices," said acting bureau director Thomas Mesenbourg.

Starting this week, more than 3.5 million U.S. households randomly selected each year to participate in the American Community Survey will be sent letters asking them to respond online. The ACS questionnaire, formerly known as the census "long form," asks households for wide-ranging details, from education and income to disabilities, language use and commute times.

The Census Bureau is also adding a series of questions on computer and Internet use to the survey, with data gathered becoming available beginning in 2014. If households don't respond within two weeks, the bureau will send out paper surveys and follow up with interviews by phone or in person.

The bureau said it is hoping to tap into the changing information habits of Americans, especially younger adults, who increasingly use tablets, smartphones and computers to communicate.

Over the last two censuses, the government has struggled with decreasing response rates from a combination of perceived inconvenience and concerns about revealing personal information in surveys.

The bureau believes higher response rates could eventually reduce costs, mainly by decreasing the need to mail out voluminous forms or dispatch hundreds of thousands of survey-takers each month to individual homes.

At least initially, officials estimate the switch could shave $3 million off the price of conducting the American Community Survey, which costs taxpayers $215 million a year. Survey demographic results are used in distributing more than $400 billion in federal funds for hospitals, roads and schools.

An Internet option was provided on a limited basis in 2000, but only a small fraction of households participated. By 2010, census officials had backed away from an Internet-based survey, citing concerns of hacking. The bureau has boosted digital security, requiring users to enter a randomly generated ID code to enter the survey site.

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