Harford County is a county in the U.S. state of Maryland. As of the 2010 census, the population was 244,826. Its county seat is Bel Air. Harford County is included in the Baltimore-Columbia-Towson, MD Metropolitan Statistical Area, which is also included in the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area.

Census records are very important research tools for genealogists and cultural historians. In the United States, beginning in 1790, the census was taken every ten years. The 1890 census, however, was lost in a fire in 1921 and only fragments survived, but none for Maryland. This two-volume compilation is a reconstruction of that census for Harford County, which identifies approximately 90% of the 28,980 people in Harford County at that time. Since the original 1890 census for Harford County was lost, every scrap of information about it is like mining for gold. Information was gleaned from a variety of sources, including newspapers, death records, church records, Bible records, cemetery records, tombstone inscriptions, funeral home records, court records, probate records, naturalizations, school records, marriage records, military records (including the 1890 Special Census of Civil War Veterans compiled by L. Tilden Moore), business records, local histories, family histories, and Find a Grave online. A considerable amount of time was also spent researching and correcting errors discovered in many primary and secondary sources. This compilation is more than a reconstructed census of names, dates, and places. It is also a directory that includes businesses, churches, and civic, social, and political organizations, i.e., a snapshot of the life activities and experiences of many of the citizens in 1890, including vocations, avocations, and more. Unlike the census, it includes full names, maiden names, married names, and nicknames in many cases. In addition to places of origin and family relationships, it also includes places of residence, dates of birth and death, and places of burial for most of them, and baptisms and divorces for some of them.

Originally published in 1993, we have split the original work into two parts and added a supplement containing the 1775 census and two hundreds (subdivisions) of the 1776 census (which were inadvertently omitted from the initial publication) and corrections. This represents a collection of data covering the period: 1773 (when the county was formed) through 1790. Volumes 1 and 2 have been extracted from the following: tax lists of 1774, 1776 (missing two Hundreds now contained in the supplement), 1778, 1783; censuses of 1776 and 1790; Dr. Archer's ledgers; orphans' court proceedings; family Bibles; estate administrations; registers of St. John's and St. George's; Quaker monthly meetings of Deer Creek and Little Falls; wills; court minutes; commercial licenses; survey certificates; land records index; marriage licenses; gleanings from various publications such as the Bulletin of the Historical Society of Harford County and other periodicals and histories; list of Non-Associators and Non-Enrollers in 1775; tombstone inscriptions; and other data drawn from the author's research and collections. This series contains over 30,000 entries.