This list, as mentioned in Needled to Death, includes historical mysteries and historical romances set in the 18th and 19th centuries. Be aware that the steam level in the romances varies!

Murder in Westminster: A Riveting Regency Historical Mystery by Vanessa Riley (Part of the Lady Worthing Mysteries series)

Nobody's Princess by Erica Ridley (Part of The Wild Wynchesters series)

Talk Sweetly to Me by Courtney Milan (Part of The Brothers Sinister series)

Rebel by Beverly Jenkins (Part of the Women Who Dare series)

An Extraordinary Union: An Epic Love Story of the Civil War by Alyssa Cole (Part of The Loyal League series) (Also check out her contribution to the anthology Marple: Twelve New Mysteries and and her modern thriller When No One Is Watching.

The Allure of a Reformed Rogue by Hildie McQueen (Part of the Regency in Color series, which also includes books by Elise Marion, Gabrielle Carr, Jessica Cale, Celeste Barclay, Robecca Austin, S. Cinders, Cecilia Rene, and Merry Farmer)

That, My Dear, Is Love: A Cozy Regency Fairytale by Sula Sullivan (Part of the Regency Revisited series)

Heart of a Slave by Verna Cyril

What the Earl Desires by Aliyah Burke (Part of the Rakes & Rogues series)

The Widows of Malabar Hill by Sujata Massey (Part of the A Perveen Mistry Novel series)

A Caribbean Heiress in Paris: A Historical Romance by Adriana Herrera (Part of the Las Léonas series)

True Love: A Story of English Domestic Life by Sarah E. Farro (copyrighted in 1891 and available at Project Gutenberg)