I see them in the neighborhood, flying halfway up the three flagpoles that grace our block. I saw a large one yesterday, what I think of as a “highway flag,” which I typically associate with the lonely off-ramps of midwestern interstates but which, for some reason, was flying over a car dealership on Route 7 in Loudon County.

Whether small or super-size, the flags have one thing in common: they are all flying half-mast. And for once I know why. I know that they honor the 39th president of the United States, the president who lived the longest, the only one to reach the age of 100.

I’ve read much about James Earl Carter Jr. these last few days. I’ve remembered his many accomplishments, recalled his trials and failures, his rich and noble post-presidency, including a Nobel prize. Here was a president who was alive at the same time as William Howard Taft and has only just gone to his reward.

So often these days I don’t know who or what half-mast flags are about. This time I do, and I realize anew the importance of this tradition, its invitation to remember, to grieve. American flags will be flying at half-mast for 30 days for President Jimmy Carter.

(A flag flies half-mast at Ball’s Bluff Battlefield Memorial Park in Leesburg, Virginia, last Memorial Day.)