No. Harriet Tubman was one of the most significant and heroic figures in American history and was born into slavery on the eastern shore of Maryland (https://visitdorchester.org/harriet-tubman-american-hero/). There was even a high school on old Guildford Road, opened in 1949, that was named after her followed by renaming of that portion of the road to Harriet Tubman Lane. But there is no record that she was ever in Howard County.
Some well-intentioned "oral history" claims place Harriet Tubman leading the enslaved to freedom by either hiding/sleeping in the Locust Church cemetery or using the Middle Patuxent River as a hiding place and escape route. (see for example https://www.visithowardcounty.com/blog/post/harriet-tubman-the-simpsonville-freetown-legacy-trail/).
No oral history sources have been provided and this continued "heritage" approach to history must be credible to best honor those mentioned. There was no reason for Harriet Tubman to even be in Howard County and no evidence that the Middle Patuxent River or the Freetown area (one greatly exaggerated in the posts) was ever used as a route for Harriet Tubman for the underground railroad. We know there were enslaved people that escaped from this area but there is no documented escape route (yet), particularly dealing with the tiny Middle Patuxent River that would have led in both directions to slave plantations.
One complicating factory to the story of Harriet Tubman visiting Freetown is that the land for Locust Church (then called Locust Chapel) was not purchased until 1868, well after the end of slavery when Harriet Tubman was living in the state of New York. There was no known cemetery prior to this time, and in fact, in the 1980s African American researcher Beulah Buckner found the earliest grave marker to be dated to 1901, although there certainly could have been earlier ones.
While Howard County would love to count the narrative of Harriet Tubman to the honored guests of this county, we can not make that claim. But we should still learn and teach about this incredible American hero born in Maryland.
Sources
Martenet, S. J. (1860) Martenet's Map of Howard County, Maryland: drawn entirely from actual surveys. Baltimore: John Schofield. [Map] Retrieved from the Library of Congress, https://www.loc.gov/item/2002624032/.
April 8, 1868. William Reynolds Jr Trustee Deed to Jeremiah Wilson 12 acres 100 sq perches. Howard County Circuit Court (Land Records) WWW 28, p. 0273, MSA_CE53_19. Date available 11/06/2003. Printed 02/18/2022
August 19, 1869. Jeremiah Wilson Deed to the Trustees of Locust Chappel - half acre. Howard County Circuit Court (Land Records) WWW 29, p. 0358, MSA_CE53_20. Date available 01/14/2015. Printed 02/18/2022.
Unpublished collection of personal research conducted by Beulah M. Buckner that was in possession of Howard County Department of Recreation and Parks and was given to the Howard County Historical Society, Inc.