ImageThe South Florida Sun Sentinel newsroom after the paper was awarded the Pulitzer Prize for public service for its coverage of the massacre at Marjory Stoneman Douglas High School.CreditCreditReutersPulitzer Prizes were awarded on Monday to news organizations that uncovered instances of malfeasance and outright fraud in President Trump’s financial past, a nod to journalists’ perseverance in the face of the president’s ever-sharper attacks on a free press.The New York Times received the explanatory reporting prize for an 18-month investigation that revealed how the future president and his relatives avoided paying roughly half a billion dollars’ worth of taxes. The Wall Street Journal won the national reporting prize for disclosing clandestine payoffs by the president’s associates to two women who were said to have had affairs with Mr. Trump in the weeks before the 2016 election.ImageCreditSouth Florida Sun SentinelThreats to journalists, foreign and domestic, provided a backdrop for this year’s prizes, which also recognized reporters forced to cover deadly tragedies in their hometowns and, in one case, their own newsroom.The South Florida Sun Sentinel won the prize for public service, considered the most prestigious of the Pulitzers, for documenting the massacre at Marjory Stoneman Douglas High School in Parkland. The paper’s in-depth articles revealed a series of failures by local officials and law enforcement that, the paper wrote, cost children their lives.The Pittsburgh Post-Gazette won for breaking news coverage of a gunman’s spree at the Tree of Life synagogue. The Pulitzer board also recognized The Capital Gazette of Annapolis, Md., where five employees were killed in a shooting in June, with a special citation that included a $100,000 bequest. Dana Canedy, the awards’ administrator, cited the Gazette’s “unflagging commitment to covering news at a time of unspeakable grief.”ImageSusanne Craig addressing The New York Times newsroom after she, Russ Buettner, to her immediate right, and David Barstow, to Mr. Buettner’s right, won the Pulitzer Prize for explanatory reporting. CreditHiroko Masuike/The New York TimesInvoking the murder of Jamal Khashoggi, The Washington Post columnist killed in Turkey by Saudi assassins, she praised this year’s journalists for a willingness to speak truth to power. “This year’s winning work reflects yet again a steely resolve in upholding the principles of this noble profession,” Ms. Canedy said.In honoring The Sun Sentinel, The Post-Gazette and The Capital Gazette, the Pulitzer board underlined the importance of local journalism at a moment when regional papers are struggling to survive. The awards, first given in 1917, are presented annually by Columbia University for excellence in journalism and letters.The Times’s investigation into Mr. Trump’s family finances, by the journalists David Barstow, Susanne Craig and Russ Buettner, drew on tens of thousands of pages of confidential records and previously undisclosed tax returns. The award was the fourth Pulitzer win for Mr. Barstow.ImageOne of the pictures that earned the the photography staff of Reuters the Pulitzer Prize for breaking news photography for coverage of the flow of migrants from Central and South America.CreditAdrees Latif/ReutersThe Times also won the prize for editorial writing, for essays by Brent Staples, a member of the paper’s editorial board since 1990, that examined race and memory in communities in Texas and New York.The Times Magazine shared in the award for feature writing, given to the ProPublica journalist Hannah Dreier, for capturing the plight of Salvadoran immigrants caught up in a federal crackdown on MS-13 gang members on Long Island.[Here’s the full list of winners.]Among the year’s other winners were Wa Lone and Kyaw Soe Oo, two Reuters journalists who have been imprisoned for more than a year in Myanmar. Their reporting, on a military crackdown and human rights violations against Rohingya Muslims in the Southeast Asian nation, shared the prize for international reporting. Coverage by The Associated Press, of atrocities in Yemen, was also recognized.Image”Frederick Douglass: Prophet of Freedom,” by David W. Blight, winner of the Pulitzer Prize for history.CreditSimon & Schuster, via Associated PressPhotography awards went to Reuters, in the breaking news category, for its visual narrative of migrants journeying north toward the United States border; and to Lorenzo Tugnoli of The Washington Post, for documenting a devastating famine in Yemen.Carlos Lozada, the book critic of The Washington Post, won the award for criticism. Tony Messenger of The St. Louis Post-Dispatch received the commentary prize for columns about rural Missourians faced with unaffordable fines for minor offenses.The Los Angeles Times, after a period of grueling ownership changes and staff unrest, received the prize for investigative reporting after the paper revealed widespread accusations of sexual abuse by a gynecologist at the University of Southern California. The reporting, by Matt Hamilton, Harriet Ryan and Paul Pringle, in part led to the resignation of the university’s president.The Advocate, of Baton Rouge, La., received the prize for local reporting for an examination of Louisiana’s criminal justice system, including a Jim Crow-era law that disproportionately affected African-Americans.Correction:April 15, 2019An earlier version of this article misstated the category in which The Wall Street Journal won a Pulitzer Prize. It won the category of national reporting, not investigative.