Anjali Enjeti is an essayist, critic and board member of the National Book Critics Circle.

On Christmas Eve in 2014, Ashley DeLeon attempted to restrain her father, Rosendo DeLeon, while he shot up their family home. “He just kept shooting and kept shooting.” A decorated Marine veteran who had served 22 years before retiring as a master sergeant, Ashley’s father suffered from severe post-traumatic stress disorder. After he was admitted to the hospital, on Christmas Day, Ashley wrote a 2 1/2 -page letter to President Barack Obama. “I didn’t care if I died Mr. President. I’m 21 years old and I would sacrifice myself without a second thought to save the man who raised me from taking his own life.” When she received a handwritten response a few weeks later from the president himself, she was shocked. “Please know that beneath the pain, your father still loves his daughter, and is surely proud of her.”

Who writes letters to the president of the United States, and what happens to these letters after they are sent? In her latest book, “To Obama: With Love, Joy, Anger, and Hope,” Jeanne Marie Laskas, the author of eight books, including “Concussion,” follows the path of constituent letters to the White House — and what happens then.

There is little documentation of how previous administrations handled constituent mail. George Washington replied to the five or so letters he received every day. William McKinley spearheaded the creation of the Office of Presidential Correspondence (OPC) to manage the hundreds he received every week. Bill Clinton read a stack every few weeks. George W. Bush seemed more interested in reading the replies the OPC would send on his behalf than the letters themselves.

When Obama moved into the White House in January 2009, he instituted a formal policy to read 10 letters a day — “10LADs,” as they became known. The 10LADs came from the unemployed: “My generation was always told that if we worked hard and did well in school and stayed out of trouble we’d have secure futures. We were lied to, or at the very least misled”; the undocumented: “I feel like you voted for me with DACA and all your efforts with the DREAM act. Thank you”; and those pleading for marriage equality: “I kept telling myself that I ‘knew’ you supported us, even if it didn’t make political sense for you to say so.”

In the mail room of the OPC, an operation that ran as seamlessly and precisely as a ballet, 50 staff members, 26 interns and hundreds of volunteers culled, categorized and curated the 10,000 letters they received each day. The 10LADs sent to the president reflected the joys, fears and struggles of Americans. Obama carried them to the residence wing every night, where he either penned replies on White House notecards or passed them on to the writing team to respond.

Obama was a president deeply affected by the suffering of the nation’s people, and the concerns expressed in the letters he received were reflected in his speeches and policies. Case in point: Less than two months after he received Ashley’s letter, he signed the Clay Hunt Suicide Prevention for American Veterans Act into law. (Sadly, Rosendo DeLeon would die later that spring in a motorcycle accident.)

“To Obama” is an insightful study of a president who listened to even his harshest critics with grace and humility. “I know things are tough out there right now,” Obama replied to the unemployed letter-writer, “and I won’t try to pretend that I’ve got a guaranteed solution to your immediate situation.” This is a story, too, about the keen judgment of the staff who appreciated the intimacy and the power of the written word, and who knew their president well enough to recognize what he not only wanted to read but also needed to read.

Curiously absent from the book are letters the OPC must have received from birthers, tea partyers and other pre-MAGA prototypes questioning Obama’s U.S. citizenship and misidentifying his religion — no doubt bigoted missives that captured the racial hatred and resentment many harbored for the black president in the Oval Office. (Letters containing direct threats to the president and his family were siphoned off and delivered to a specific full-time staffer at the OPC to be assessed further.) The OPC may have refused to share these letters with Laskas, or perhaps the authors of the letters refused to grant her permission to print them. Regardless, their inclusion would have provided insight into that constituency.

If there is a singular lesson about the White House letters during the Obama administration, it is that for eight years the distance from a constituent’s abode to the Oval Office was short and that the president who signed his name with a rotund “B” and a generous “O” approached correspondence from the people with tenderness, awe and respect. At the end of each presidential day, Obama saw himself as one of them. “We have this idea that the president is so much larger than us and that he’s this other type of person,” said Ashley DeLeon. “But he’s exactly like we are.”

To Obama

With Love, Joy, Anger, and Hope

By Jeanne Marie Laskas

Random House. 401 pp. $28