From the late 18th century into the 1820s Baltimore was a "city of transients," a fast-growing boom town attracting thousands of ex-slaves from the surrounding countryside. Slavery in Maryland declined steadily after the 1810s as the state's economy shifted away from plantation agriculture, as evangelicalism and a liberal manumission law encouraged slaveholders to free enslaved people held in bondage, and as other slaveholders practiced "term slavery," registering deeds of manumission but postponing the actual date of freedom for a decade or more. Baltimore's shrinking population of enslaved people often lived and worked alongside the city's growing free black population as "quasi-freedmen." With unskilled and semiskilled employment readily available in the shipyards and related industries, little friction with white workers occurred. Despite the overall poverty of the city's free blacks, compared with the condition of those living in Philadelphia, Charleston, and New Orleans, Baltimore was a "city of refuge," where enslaved and free blacks alike found an unusual amount of freedom. Churches, schools, and fraternal and benevolent associations provided a cushion against hardening white attitudes toward free people of color in the wake of Nat Turner's revolt in Virginia in 1831. But a flood of German and Irish immigrants swamped Baltimore's labor market after 1840, driving free blacks deeper into poverty.