Merchants in downtown Lawrence are hoping that a $25,000 investment pays off this holiday season with more shoppers and, ultimately, more spending.

Downtown Lawrence Inc. this year bought 9,500 new holiday lights to adorn the rooftops of buildings in the central business district.

“We need a festive mood,” said Maria Martin, president of the business group and owner of Southwest and More, 727 Mass. “Without lights, it wouldn’t be the holidays.”

The new strands — stretching for 1.8 miles — plug into 49 individual timers, each set to beam their clear, 7-watt bulbs at 6 p.m. each day, starting Friday.

The lights replace the downtown association’s old ones, which had been strewn for years in the trees along Massachusetts Street. That practice stopped this year, after city officials deemed the electrical conduits in planter boxes too old, unreliable and unsafe for another season’s use.

“We actually had an employee who was shocked last year,” City Manager Mike Wildgen said. “(The employee)’s fine, but that combination of water and power — it’s not a good combination.”

The association’s 165 members financed the bulk of the new lights. Of the $25,000 cost for the purchase, installation and ongoing maintenance, $7,000 came from city taxes generated by stays in hotel rooms, and $1,000 came from the Lawrence Chamber of Commerce.

The lights are part of a campaign to convince people from near and far to add the district to their shopping lists. Downtown merchants are coordinating advertising in Kansas City, Wichita, Omaha, Neb., and Des Moines, Iowa, to help draw people in.