Severna Park riders and others who have lobbied to keep the No. 210 bus, which goes from Annapolis to Baltimore, have a year to recruit 100 daily passengers for the line.
The Mass Transit Administration agreed several months ago to retain the line and reinstate evening trips that had been cut.
But this week, the MTA announced a ridership goal for the No. 210 that must be met to make the line cost-efficient, said MTA spokeswoman Dianna Rosborough.
"When the decision to retain the No. 210 was made, the line was losing money," she said. "One hundred new passengers would make it financially feasible to run the service."
Without the additional passengers, Ms. Rosborough said, the MTA likely would be forced to cut the line.
Last year, the MTA only recovered 19 percent of what it spent to run the No. 210, Ms. Rosborough said. The line averaged 269 riders daily.
Adding 100 riders a day would "almost double it to about 40 percent, putting it nearer the state-mandated 50 percent recovery," Ms. Rosborough said. The 50 percent goal applies to the aggregate of bus lines, not individual ones.
To reach the goal, the MTA has begun marketing initiatives, including more advertising, direct mail and word-of-mouth selling.
One No. 210 rider, Margaret Coleman of Severna Park, said she (( thought adding 100 people was possible but wouldn't happen quickly.
Ms. Coleman, a paralegal with a law firm at the Inner Harbor in Baltimore, joined a committee of No. 210 riders meeting monthly with the MTA about the line.
"The MTA is doing all they can to work with us," she said. "Now the ball is in our court. We're doing what we can to stimulate ridership. We've solicited riders from the No. 220 line, which was discontinued in August. We've passed out bus schedules, which have always been scarce."
Ms. Coleman said she thought more people would ride if they realized how inexpensive and convenient the bus is.
"A lot of Severna Park people like the idea, but I think they have a lot of misconceptions about who rides the bus," she said. "I find that quite bewildering. Very nice people ride the bus. People who get up and go to work every day like you and me. They have families and people at home waiting for them."
Ms. Coleman said she and other riders believe the federal Clean Air Act, which mandates that cities such as Baltimore take steps to reduce air pollution, could force major corporations to increase the use of public transportation.
A recent survey of No. 210 bus line riders found that almost 40 percent learned about the service from someone else who rode it, Ms. Rosborough said.
Survey results are being used to plan and market the line in the future, she said.
The No. 210 begins in Annapolis and travels through Severna Park to Baltimore. The bus stops in Arnold, at the park-and-ride lot in Severna Park, at Baltimore and Annapolis Boulevard and McKinsey Road and at Ritchie Highway and Earleigh Heights before stops beyond Severna Park.
The MTA last year had proposed reducing service on the No. 210. Those who rode the bus attended public hearings and begged the MTA to continue the line.
Greater Severna Park Council member Ellen McGee-Keller also testified in support of the No. 210 at MTA hearings. The council, an umbrella organization of civic groups, sent protest letters to elected officials, and council members signed petitions. The MTA then decided to use the line as a marketing trial aimed at increasing ridership.