Consider two extremes of tourism: In Tombstone, Ariz., 1,100 residents host some 600,000 visitors a year who stay an average of two hours and spend just $8 each.

In the Republic of Ireland, the government maintains the rural landscape as well as a strong sense of community and history while its economy soars and it attracts millions of tourists each year.

In the first case, businesses overwhelm a community and extract every dollar they can — money that largely goes elsewhere. In the second, an entire country makes use of tourism revenues to support its historic communities, farms and landscapes.

Those two extremes were offered recently by tourism expert Dan Shilling as he explained to 50 local planners and tourism officials why his concept of "civic tourism" is preferable to the industrial-age tourism that has long prevailed around the world.

"Civic tourism preserves and enhances a community rather than uses a community," said Shilling, the keynote speaker at a conference on sustainable tourism hosted at the Blackstone Valley Visitor Center in Rhode Island by the Blackstone Valley Tourism Council.

The council's director, Robert Billington, said his challenge has been to attract visitors to a part of Rhode Island that doesn't have beautiful beaches or great mansions. It is a place, he said, that probably created the first grossly polluted river in the hemisphere during the Industrial Revolution.

Billington said his council is constantly questioning whether it is promoting the Blackstone Valley properly. He has been in the tourism business for 25 years and is constantly looking for new ideas.

The state, he pointed out, committed to the related concept of geo-tourism last year. Rhode Island joined Arizona, Guatemala, Honduras and Norway by signing a Geotourism Charter with the National Geographic Society that committed the state to preserve and protect its unique assets such as Narragansett Bay and the colonial architecture in Newport and Providence.

Shilling and Billington are organizing an international conference on civic tourism that will be held during three days in October in Rhode Island.

Consider these changes in the last 50 years:

• Some 25 million international arrivals to the U.S. took place in 1950; in 2005, the number soared to 750 million.

• The number of museums in the U.S. grew from 2,400 in 1950 to 17,500 in 2005.

• Tourism is now the first-, second- or third-largest industry in every state in the U.S. It is the largest industry in the world.

• While many of the parents of baby boomers never left the country, many boomers have. They have more money than any generation in history, and they want to spend it on experiences, not things. They want to travel to unique, authentic places.

Shilling suggested that rather than following the traditional practice of evaluating only the economic bottom line, tourism ventures should be evaluated with a "triple bottom line" that also looks at the social and environmental results.

He rejected the notion that communities must choose between the environment and the economy.

Three states that rank near the top on environmental investments also rank near the top economically. They are Vermont, New Hampshire and Hawaii.

Three states rank near the bottom in both categories. They are Mississippi, West Virginia and Louisiana.