BOSTON — Of the 146 starters in the women’s United States Olympic marathon trials Sunday, the oldest was 50-year-old Joan Benoit Samuelson.

In 1984, she won the first Olympic marathon for women, but her goals now are more modest. Two weeks ago, she said she hoped to run the marathon in 2 hours 50 minutes. On Friday she said, not completely in jest, “My goal is getting to the starting line and getting to the finish line.”

On a crisp Sunday morning, she accomplished all of that. She finished in 2:49.08, putting her 90th among the 124 finishers, and giving her an American record for the women’s 50-54 age group. Along the roads in Boston and Cambridge, she received the loudest cheers of any runner.

“The support around the course was unbelievable,” she said. “I ran a very conservative race. All I wanted was to break three hours and finish.”

Samuelson has been a favorite here since 1979, when she unexpectedly won the Boston Marathon. She finished that race wearing a Red Sox cap given to her by a spectator. This time, she started with a white cap and finished with another Red Sox cap.