The UCLA Anderson School of Management has recognized two ProPublica investigations as winners in its 2018 Gerald Loeb Awards, one of the most prestigious honors in business journalism.

ProPublica Illinois — the nonprofit newsroom that launched last year as ProPublica’s first regional, state-based unit — and the Chicago Tribune won the Loeb Award in the local category, for their joint “The Tax Divide” investigation into Cook County, Illinois’ unfair property tax assessment system.

For decades, controversy had swirled around the assessment system in Cook County, the largest in Illinois. Residents and business owners had suspected their property taxes were based on inaccurate assessments, overvaluing many low-priced properties while undervaluing many higher priced ones. Lead reporter Jason Grotto (who started the project as a Chicago Tribune staff writer and continued his investigation after joining ProPublica Illinois) set out to prove statistically that the assessment system was deeply flawed. The resulting four-part series exposed widespread inequities and egregious errors in assessments that punished small businesses and poor homeowners, while giving the wealthy unsanctioned tax breaks and lining the pockets of politically connected tax attorneys.

Grotto and his team, which included ProPublica Illinois data reporter Sandhya Kambhampati and Chicago Tribune reporter Hal Dardick, sparked swift impact with their investigation. The inspector general for Cook County launched an investigation almost immediately, and the county board required Assessor Joseph Berrios to testify at a public hearing about his methods. Three prominent public interest law offices sued Berrios and the county, drawing heavily on “The Tax Divide” and alleging violations of state and federal civil rights and housing laws. In the Illinois primary election in March, Berrios was voted out.

The “Automating Hate” series won the Loeb Award for beat reporting. The collaboration with the New York Times and a coalition of German news organizations — by Julia Angwin, Jeff Larson, Ariana Tobin, Madeleine Varner, Noam Scheiber and Hannes Grassegger — exposed an underside of Facebook’s success by documenting policies that the world’s largest social network had long hidden.

Reporting on secret guidelines that Facebook’s censors use to distinguish between hate speech and legitimate political expression, the series revealed internal documents that lay out Facebook’s rationale behind seemingly inconsistent decisions on the user posts it deletes. The piece disclosed that white men fall under protected categories of people — based on gender, race or religious affiliation — but black children do not. Following the story, Facebook changed its rules to add age as a protected category, an adjustment that will lead to the deletion of some slurs.

ProPublica further investigated Facebook’s ad-buying platform. We found that advertisers were able to tailor their pitches to people who had expressed interest in such topics such as “Jew hater” or “History of ‘why Jews ruin the world.’” When asked about this before publishing the article, Facebook removed the categories. After the story, the company said it would add more human reviewers, create a way for people to report abusive ad categories, and step up enforcement of the company’s rules against hateful targeting.

The series also revealed that Facebook and other major platforms were allowing employers to place recruitment ads limited by age. Older workers never saw the ads. The two ranking members of the U.S. Senate Special Committee on Aging sent a letter to employers and tech companies raising questions about the practice.