WASHINGTON - The rising cost of college textbooks has driven Congress and nearly three dozen states to attempt to curtail prices and controversial publishing practices through legislation. But as the fall semester begins, students are unlikely to see much relief.

Estimates of how much students spend on textbooks range from $700 to $1,100 annually, and the market for new books is estimated at $3.6 billion this year.

Between 1986 and 2004, the price of textbooks nearly tripled, rising an average of 6 percent a year while inflation rose 3 percent, according to a 2005 report by the Government Accountability Office. In California, the state auditor reported last week that prices have skyrocketed 30 percent in four years.

"It's really hard just paying for tuition alone," said Annaiis Wilkinson, 19, a student at Trinity University in Washington who spends about $500 a semester on books.

In July, Congress passed legislation forcing publishers to release more pricing information. It also requires them to sell a textbook separately rather than packaged with a CD or workbook, which raises costs . But the provisions do not take effect until 2010.

"The principal goal of the legislation, which we are totally supportive of, is transparency," said Bruce Hildebrand, executive director of higher education for the Association of American Publishers, a trade group. "It's what the industry already does."

Costs for new textbooks have risen as publishers have tried to fight off an expanding trade in used books. The market for used textbooks began exploding with the growth of the Internet as students from across the country connected to buy and sell their books, cutting into the sales of new books and eating away at publishers' market share.

Sales of used textbooks last year grew 15 percent to $2 billion, with double-digit growth expected through 2011, according to Simba Information, a market research group. Sales of new textbooks have grown 4 to 5 percent annually, with the market this year expected to reach $3.6 billion.