Early in 2004, at a party for Washington area school leaders, Jack D. Dale, head of the Frederick County, Md., system, let slip that he had gotten a big new job running the Fairfax County schools. Jerry D. Weast, the Montgomery County superintendent, who was also there, later told somebody who leaked it to me, one of my rare scoops.

For the next seven years, Dale and Weast were the most powerful school chiefs in the region. They ran two of the largest, most affluent and highest-performing school systems in the country.

Now, new people are or will be filling those roles. Weast retired in June and was succeeded by Joshua P. Starr from Stamford, Conn. Dale announced last month that he will leave in 2013. What can we learn from comparing Dale and Weast? Will that help us understand why or if superintendents matter?

Both were thoughtful and friendly with journalists, but Weast was much more aggressive. He sometimes invited himself to The Washington Post’s office on 15th Street NW to unveil his latest analysis of student achievement. His rapid-fire data explanations required close attention. He was more competitive than Dale, asking each spring whether Montgomery had more high schools on my 100 most-challenging list than Fairfax.

Both superintendents knew the more important fact was that their two systems were the largest in the country to have every single high school meet my criteria for challenge and thus rank in the top 5 percent nationally. When I totaled the 2010 ratio of college-level tests to graduating seniors in each county, the results were essentially identical — 3.185 for Montgomery and 3.164 for Fairfax.

Dale’s and Weast’s systems are still close in most important measures. Fairfax has a slight edge in average state test and SAT scores, probably because it has a slightly smaller portion of students from low-income families — 25 percent, to 31 percent in Montgomery. The achievement gap between whites and blacks is about 10 points in Fairfax and 13 points in Montgomery. The average SAT score in Fairfax for the Class of 2011 is 1654, out of 2400, and 1637 in Montgomery.

Fairfax eighth-graders had a 95 percent proficiency rate in reading and 90 percent in math in the 2010-2011 school year. In Montgomery, those rates were 89 percent and 75 percent. They are in different states with different measures of proficiency, so comparing those numbers doesn’t get us far.

Weast got much notice for his well-organized effort to raise the achievement of poor children by giving them intensified reading instruction in their early years. Dale did not receive as many headlines, but his county also focused on disadvantaged children and had remarkable college preparation successes in high schools with mostly poor kids.

Dale was in political trouble more often than Weast because he had a larger and more ideologically divided district. Well-organized parent groups in Fairfax pushed Dale to change high school opening times to help sleep-starved teens, alter the report card grading system to give students a better chance at colleges and scholarships, and soften a knee-jerk response to student misbehavior. He found ways to satisfy critics on grades and discipline. The sleep issue will rise again, but like Weast, Dale managed to weather most of the storms.

The secret of their success, usually not mentioned when their records are analyzed, has as much to do with the people who put them in their jobs as with their individual gifts.

Often in systems as large as Fairfax (175,000 students) and Montgomery (144,000), school boards are as much an impediment as a boost to learning. So in the 14 years I have been watching those counties closely, the high quality of their elected leadership has often surprised me. Both have been blessed with board members who understand how school improvement has to work and were willing to pick superintendents smarter than they were and let them do their jobs.

The two counties have high family incomes and education levels, but those do not always correlate with intelligent school boards. I think Fairfax and Montgomery lucked out, but that is still worth celebrating. Say a fond farewell to Dale and Weast, and pray that good fortune keeps smiling on their two systems.