Population growth
Year          Population  
1790            14,000 
1800            27,000 
1810            47,000 
1820            63,000 
1830            81,000 
1840           102,000 
1850           169,000 
1860           212,000 
1870           267,000 
1880           332,000 
1890           434,000

Baltimore grew rapidly, becoming the largest city in the American South. It dominated the American flour trade after 1800 due to the milling technology of Oliver Evans, the introduction of steam power in processing, and the merchant-millers' development of drying processes which greatly retarded spoilage. Still, by 1830 New York City's competition was felt keenly, and Baltimoreans were hard-pressed to match the merchantability standards despite more rigorous inspection controls than earlier, nor could they match the greater financial resources of their northern rivals.

Finance
Alexander Brown (1764–1834), a Protestant immigrant from Ireland, came to the city in 1800 and set up a linen business with his sons. Soon the firm Alex. Brown & Sons moved into cotton and, to a lesser extent, shipping. Brown's sons opened branches in Liverpool, Philadelphia, and New York. The firm was an enthusiastic supporter of the B&O Railroad By 1850 it was the leading foreign exchange house in the United States. Brown was a business innovator who observed social conditions carefully and was a transition figure to the era after 1819 when cash and short credits became the norms of business relations. By concentrating his capital in small-risk ventures and acquiring ships and Bank of the United States stock during the Panic of 1819, he came to monopolize Baltimore's shipping trade with Liverpool by 1822. Brown next expanded into packet ships, extended his lines to Philadelphia, and began financing Baltimore importers, specializing in merchant banking from the late 1820s to his death in 1834. The emergence of a money economy and the growth of the Anglo-American cotton trade allowed him to escape Baltimore's declining position in trans-Atlantic trade. His most important innovation was the drawing up of his own bills of exchange. By 1830 his company rivaled the Bank of the United States in the American foreign exchange markets, and the transition from the 'traditional' to the 'modern' merchant was nearly complete. It became the nation's first investment banking. It was sold in 1997, but the name lives on as Deutsche Bank Alex. Brown, a division of the Germany's Deutsche Bank.

Peabody and Philanthropy
George Peabody rose from humble beginnings to become one of the nation's most powerful businessmen. Based in Baltimore, Peabody developed an extensive network of financial and mercantile institutions that laid the groundwork for J. P. Morgan's financial empire. Peabody relocated to London in 1837 and later helped install the first transatlantic telegraph cables. During the 1860s, Peabody began his celebrated philanthropic career, endowing libraries and museums and aiding the poor on both sides of the Atlantic. He founded the Peabody Institute which included a library, an academy of music, and an art gallery and which, he hoped, would aid the moral and intellectual development of the citizenry. Peabody's legacy inspired Andrew Carnegie and other captains of industry to offer some of their wealth to serve the public good.

Baltimore and Ohio Railroad
Baltimore faced economic stagnation unless it opened routes to the western states, as New York had done with the Erie Canal in 1820. In 1827, twenty-five merchants and bankers studied the best means of restoring "that portion of the Western trade which has recently been diverted from it by the introduction of steam navigation." Their answer was to build a railroad—one of the first commercial lines in the world. The Baltimore and Ohio Railroad became the first chartered railroad in the United States; twenty thousand investors purchased $5 million in stock to import the rolling stock and build the line. It was a commercial and financial success, and invented many new managerial methods that became standard practice in railroading and modern business. The B&O became the first company to operate a locomotive built in America, with the "Tom Thumb" in 1829. It built the first passenger and freight station (Mount Clare in 1829) and was the first railroad that earned passenger revenues (December 1829), and published a timetable (May 23, 1830). On December 24, 1852, it became the first rail line to reach the Ohio River from the eastern seaboard.

Blacks
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 owners to liberate those in bondage, and as other masters practiced "term slavery," registering deeds of manumission but postponing the actual date of freedom for a decade or more. Baltimore's shrinking slave population often lived and worked alongside the city's growing free black population as "quasi-freedmen." With unskilled and semiskilled employment readily available, particularly 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 slave and free black alike found an unusual amount of freedom. Churches, schools, and fraternal and benevolent associations provided a cushion against hardening white attitudes toward free blacks 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.
The Maryland Chemical Works of Baltimore used a mix of free labor, hired slaves, and slaves owned by the corporation to work in its factory. Since chemicals needed constant attention, the rapid turnover of free white labor encouraged the owner to use slaves. While slave labor was about 20% cheaper, the company began to reduce its dependence on slave labor in 1829 when two slaves ran away and one died.[9]
It was easy for slaves in the city to run away—as Frederick Douglass did. Therefore slaveholders in Baltimore frequently turned to gradual manumission as a means to secure dependable and productive labor from slaves. In promising freedom after a fixed period of years, slaveholders intended to reduce the costs associated with lifetime servitude while providing slaves incentive for cooperation. Blacks for their part tried to negotiate terms of manumission that were more advantageous, and the implicit threat of flight weighed significantly in slaveholders' calculations. The dramatic decrease in the slave population during 1850-60 indicates that slavery was no longer profitable in the city. Slaves were still used as expensive house servants, it was cheaper to hire a free worker by the day, with the option of dropping him or replacing him with a better worker, rather than run the expense of maintaining a slave month in and month out with little flexibility.
On the eve of the Civil War Baltimore had the largest free black community in the nation. About 15 schools for blacks were operating, including Sabbath schools operated by Methodists, Presbyterians, and Quakers, along with several private academies. ll black schools were self-sustaining, receiving no state or local government funds, and whites in Baltimore generally opposed educating the black population, continuing to tax black property holders to maintain schools from which black children were excluded by law. Baltimore's black community, nevertheless, was one of the largest and most cohesive in America due to this experience.

1850s
Baltimore in the Third Party System had two-party competitive elections, with powerful bosses, carefully orchestrated political violence, and an emerging working-class consciousness at the polls. The fierce politics of the 1850s had galvanized the white workers, most of them German, who opposed slavery. The American Party emerged in the mid 1850s to represent Protestants and to counter the Democratic Party, which was increasingly controlled by Catholic Irish. When Baltimore erupted in violence at the time of Lincoln's inauguration, for example, the pro-Union "Blood Tubs" that took to the streets were veterans of political rioting. The nativist American (Know-Nothing) Party captured the Baltimore government in 1854. The party used patronage and, especially, coercion; its armed forces scared off Democratic voters and forced drunks and immigrants to vote multiple times. Voters eleted a congressman and governor nominated by the party during its short life. In 1860 the Democrat-controlled legislature took back the city police, the militia, patronage, and the electoral machinery, and prosecuted some Know-Nothings for electoral fraud. By 1861 the Know-Nothings had split over secession.

Civil War
Baltimore was torn by the Civil War. Much of the social and political elite favored the Confederacy—and indeed owned house slaves. In the 1860 election the city's large German element voted not for Lincoln but for Southern Democrat John C. Breckinridge. They were less concerned with the abolition of slavery, an issue emphasized by Republicans, and much more with nativism, temperance, and religious beliefs, associated with the Know-Nothing Party and strongly opposed by the Democrats. However the Germans hated slavery and supported the Union.
When Massachusetts troops marched through the city on April 19, 1861, en route to Washington, a rebel mob attacked; 4 soldiers and 12 rioters were dead, and 36 soldiers and uncounted rioters had been injured. Governor Thomas Hicks realized action was needed. He convened a special session of the General Assembly but moved its location to a site in Frederick, a distance from the secessionist groups. In doing this and by other actions, Hicks managed to neutralize the General Assembly to avoid Maryland's secession from the Union, becoming a hero in the eyes of the Unionists in the state. Meanwhile pro-Confederate gangs burned the bridges connecting Baltimore and Washington to the North, and cut the telegraph lines. Lincoln sent in federal troops under Gen. Ben Butler; they seized the city, imposed martial law, and arrested leading Confederate spokesmen. The prisoners were later released and the rail lines reopened, making Baltimore a major Union base during the war.