A diligent student of thousands of newspapers, census data and court documents from 19th century Baltimore has painted a previously undocumented view of slavery in the city during the pre-Civil War years.
In an unusual book, Ralph Clayton, who heads the Central Enoch Pratt Free Library's microfilm department, sketches a Baltimore in which, during the decade immediately before the Civil War, slavery was waning fast.
His research clearly confirmed that this breakdown was occurring not necessarily because of a widespread change in the moral concerns of whites, who had owned and traded in slaves almost from Maryland's beginnings as a colony.
Rather, several factors were in play, not the least of which was a doubling between 1840 and 1860 of German and Irish immigrants who were willing to work cheaply. For that reason, they found favor among many city business owners who had relied previously on the labor of slaves and free blacks.
"The population of the resident German and Irish citizens in the city rose from 21,000 in 1850 to 48,000 in 1860. Inexpensive immigrant labor severely impacted the free black and slave male work force, particularly in the wards [voting districts] encircling Baltimore's harbor," Mr. Clayton says.
"A lot of Afro-American males were forced out of the labor market as ship caulkers and related jobs. They had to become servants, coach drivers and waiters, where they previously had jobs requiring manual skills," he says.
At that time, a ship caulker's job was a significant position in the city's extensive shipbuilding industry.
The effect of this immigration, the city's booming economy and changing views about slavery, Mr. Clayton concludes, were profound for both slaves and the city's sizable number of free blacks.
In fact, he and other researchers note that in the 10 years before the Civil War started in 1861, Baltimore had become home for the largest free-black population of any city in the country -- free blacks outnumbered slaves by more than 8-1.
Despite the presence of so many free blacks, Mr. Clayton says, the period "was a terrible time for the black community, living under a constant fear of re-enslavement."
White kidnappers would hire free African-Americans, take them to Richmond and sell them as slaves, "using fabricated papers," he says.
For his book, entitled "Slavery, Slaveholding and the Free Black Population of Antebellum Baltimore," the 45-year-old author spent six years tediously reviewing federal census tracts, tax lists, city directories, newspapers and court papers.
Mr. Clayton's research portrays a varied picture of "urban" slavery -- and the life of free blacks -- in the mid-19th century that differs in many ways from the more widely publicized images of plantation and agrarian slavery.
Among his findings, which corroborate views of other researchers, Mr. Clayton documented as occurring in Baltimore the practice by some slave-holders of "renting" slaves to others in the city who needed help.
Baltimore newspaper advertisements in that era revealed that slaves could be rented in the 1850s to be barbers, hotel waiters, coachmen, servants, rope-makers and sawyers.
Mr. Clayton documents the fact that, contrary to what many believe today, not all slave-holders of the 1800s were wealthy. Many Baltimore slave-holders were middle-class and owners of small businesses who hired a slave as a servant or worker.
He found that before the outbreak of the Civil War, Baltimore's merchant class was the most typical social station of those whites who owned slaves.
"The upper and middle classes accounted for most of the slave-holding population, but carters, sailors, hod-carriers and common laborers with little or no real estate are documented as slaveholders," Mr. Clayton writes.
The records Mr. Clayton combed -- often coping with tiny type on blurry microfilmed photos of old, faded pages, typically handwritten -- confirmed that a number of the city's free blacks owned land and houses. All of the city's political wards had both slaves and free blacks as residents.
In a city dominated by businesses related to shipping and railroading, free blacks typically worked as stevedores, ship caulkers, seamen, brick-makers, hucksters, porters and teachers.
Physically, Baltimore was much smaller then, of course -- a city with about a quarter of today's population.
The 1850 federal census noted that Baltimore had a total population of 169,054. Of that number, about 17 percent were African Americans -- 25,442 free blacks and 2,946 slaves. Ten years later, in 1860, the population was 212,418, with 25,680 free blacks and 2,218 slaves.
"The other force was the work that Baltimore offered Afro-Americans from all over the state. Baltimore was a booming city where free blacks could get jobs. They came from the counties to work along the waterfront and in other job sites.
"Baltimore was an unusual American city," Mr. Clayton says. "Blacks have always been a part of life here. One visitor from England called Baltimore 'Little Africa' when he visited here before the Civil War."