Dingell dictated the message to his wife and congressional successor Debbie Dingell Thursday in their suburban Detroit home. The Washington Post published the opinion piece on Friday.
"One of the advantages to knowing that your demise is imminent, and that reports of it will not be greatly exaggerated, is that you have a few moments to compose some parting thoughts," Dingell said Thursday. "In our modern political age, the presidential bully pulpit seems dedicated to sowing division and denigrating, often in the most irrelevant and infantile personal terms, the political opposition."
Dingell, who died Thursday at age 92, didn't mention Trump by name in the article.
Dingell represented parts of southeast Michigan for nearly 60 years before retiring in 2014 as the longest-serving member of Congress in U.S. history.
On Friday, Trump ordered flags at the White House and other federal facilities lowered to half-staff in Dingell's memory. The president also used Twitter to extend sympathies to Debbie Dingell and other family members.
"Longest serving Congressman in country's history which, if people understand politics, means he was very smart," Trump tweeted. "A great reputation and highly respected man."
Dingell's opinion article was similar to a letter penned by former Arizona Sen. John McCain before his death in August from brain cancer.
In McCain's letter, the late Arizona Republican appeared to repudiate Trump's politics one last time, saying, "We weaken our greatness when we confuse our patriotism with tribal rivalries that have sown resentment and hatred and violence in all the corners of the globe."
Much of Dingell's letter to the Post focused on the country and improvements made over the decades to Medicare, the environment, the Great Lakes and efforts to end racial discrimination.
"All of these challenges were addressed by Congress," Dingell said. "Maybe not as fast as we wanted, or as perfectly as hoped. The work is certainly not finished. But we've made progress — and in every case, from the passage of Medicare through the passage of civil rights, we did it with the support of Democrats and Republicans who considered themselves first and foremost to be Americans."
He concluded by saying "as I prepare to leave this all behind, I now leave you in control of the greatest nation of mankind and pray God gives you the wisdom to understand the responsibility you hold in your hands. May God bless you all, and may God bless America."
Trump's proclamation applies to flags at the White House, other public buildings and grounds, U.S. military posts and naval stations, and on all federal naval vessels. They'll be lowered until sunset Saturday.
Flags at U.S. embassies and other facilities overseas also are ordered to half-staff. Michigan Gov. Gretchen Whitmer also ordered flags on state property lowered.
A public visitation will be held Monday at Ford Community and Performing Arts Center in Dearborn. A funeral will be held at a local church Tuesday.
Following those services, a casket carrying Dingell's body will be driven past the Capitol in Washington. The public is invited to watch from the east lawn of the Capitol.
A second funeral Mass will be held Thursday at 10:30 a.m. at Holy Trinity Catholic Church in Washington. The public is invited.
Dingell will be interred at Arlington National Cemetery, said his wife Debbie Dingell, who succeeded him in the Michigan congressional seat.
Tributes poured in following Dingell's death, including from former U.S. presidents, colleagues and some of his more than 250,000 Twitter followers.
See AP's complete coverage of John Dingell here: https://apnews.com/JohnDingell