a changing economy, revolutionary ideals, and preaching by Methodist and Quaker ministers, numerous planters in Maryland freed their slaves in the twenty years after the Revolutionary War . This was a pattern across the Upper South, in which the free black population increased markedly from less than 1% before the war to 14% by 1810. [ 52 ] After that, increasing demand in the Deep South , which was developed for cotton plantations, resulted in slaves being sold and transported there from the Upper South, including Maryland. The Baltimore and Ohio Railroad (B&O) was the first chartered railroad in the United States, and it opened its first section of track for regular operation in 1830, between Baltimore and Ellicott City. [ 53 ] In 1852 it became the first rail line to reach the Ohio River from the eastern seaboard. [ 54 ] Baltimore's seaport and good railroad connections fostered substantial growth during the Industrial Revolution of the 19th century. Many manufacturing businesses were established in Baltimore and the surrounding area after the Civil War. Catholics have not ever continuously been a majority in Maryland, however since the abolishment of anti-Catholic laws in the early 1830s, the Catholic population began to rebound considerably. [ 55 ] The Maryland Catholic population began it's resurgence With large waves of Irish Catholic immigration [ 55 ] spurred by the Great Potato Famine in Ireland (1845–49) and then continued through the first half of the 20th century. [ 55 ] Italian immigration [ 56