For most people, the annual ritual of daylight saving time — spring ahead, fall back — might seem about as controversial as a sunrise. But ever since the federal government began to coordinate daylight saving time throughout the country in 1967, there have intermittent skirmishes along the borders where the Eastern time zone blends into the Central, or Central into Mountain.

For more than 25 years, the nation’s disputes about time were handled by Joanne Petrie, a lawyer in the general counsel’s office of the Department of Transportation. She died July 9 under hospice care at the Hebrew Home of Greater Washington in Rockville of complications from breast cancer. She was 55.

The bulk of Ms. Petrie’s work was taken up with budget matters and regulatory issues concerning commercial aviation, highway safety and automotive standards. But she became known as “Mother Time” for the patient way that she dealt with questions about time zones and daylight saving time.

“I get a lot of strange calls,” she told the States News Service in 1997. “Like, someone’s doing their horoscope and wants to know if Colorado was under daylight saving time in 1945.”

She once helped solve a murder by establishing the time of death after a victim’s watch was found one hour off the correct time.

When she joined the Transportation Department in 1985, Ms. Petrie asked for the time-zone portfolio, which had become one of the department’s responsibilities through historical happenstance. In the 1880s, the railroads divided the continental United States into four primary time zones, which were codified into federal law in 1918.

Daylight saving time was first used during World War I and again during World War II, when it was called “war time.” After that, individual communities could decide when and whether they wanted to adopt daylight saving time, resulting in a patchwork of confusion across the country.

In the 1950s and 1960s, Boston, New York, Philadelphia and Washington did not observe the same time for five weeks of the year. Iowa had 23 different starting and ending dates for daylight saving time. There were seven time changes on one 35-mile bus route from West Virginia to Ohio.

Daylight saving time finally became standardized throughout most of the country in 1967, the same year the Department of Transportation began. Because of the historical connection between the two — time zones were created, after all, to make the trains run on time — the new Transportation Department was charged with being the nation’s timekeeper.

Despite evidence that crime and traffic accidents are reduced, daylight saving time wasn’t universally popular at the beginning, and many people complained that moving clocks ahead one hour violated the natural order of things.

“The time you get up in the morning, the time you get your kids off to school, what time you watch the evening news — these are very personal issues for some people,” Ms. Petrie said in 1997.

From time to time, she conducted public hearings to resolve disputes, including a series of contentious meetings in Indiana, which steadfastly refused to observe daylight saving time until 2006. (Arizona and Hawaii are now the only states that stay on standard time year-round.)

The Hoosier state’s peculiar sense of time was best summarized in 1996 by a gubernatorial candidate with the singularly apt name of Rex Early.

“Some of my friends are for putting all of Indiana on daylight saving time,” he said. “Some are against it. And I always try to support my friends.”

In 1989, Ms. Petrie visited Kearny County, Kan., which was divided by the Central and Mountain time zones. She listened to local residents and asked for a show of hands for their preference. The vote was almost dead even.

Ultimately, all of Kearny County was placed in the Central time zone because Transportation Department rules give priority to the needs of local commerce — proving the adage that time is money.

Joanne Grace Petrie was born Oct. 24, 1955, in Garden City, N.Y., and graduated from William Smith College in Geneva, N.Y. After completing law school at Boston University in 1980, she came to Washington and worked for the old Civil Aeronautics Board before transferring to the Department of Transportation.

She had many interests outside work and once combined two of them — travel and dance — by studying belly dancing in Morocco for a month. She was an accomplished flamenco dancer who performed internationally and later chaired the U.S. Spanish Dance Society.

She and her husband of 29 years, Vladimir Ankudinov, a scientist who fled the Soviet Union, often went on Caribbean cruises and once toured Europe by bus. Ms. Petrie later traveled across Turkey and throughout the British Isles with her daughter, Katharine, and visited her grandmother’s birthplace on Scotland’s Isle of Skye.

In addition to her husband and daughter, Ms. Petrie’s survivors include a brother. Her mother lived with the family in the Colesville section of Montgomery County for about 10 years before she died last year.

Ms. Petrie was a member of Colesville Presbyterian Church but was also interested in a broad range of spiritual ideas and had become an expert on Reiki, a Japanese healing and relaxation technique.

“She was always searching, always curious, always wanting to learn,” said Dina Bissonnette, a lifelong friend.

Ms. Petrie was an early riser and was always punctual. Even though she was the country’s leading authority on daylight saving time, the annual change often caught her off guard.

“Half the time, I forget to change the clocks myself,” she said in 1997. “I’m running around the house Monday morning, trying to figure out how to reset the VCR.”