The rail magnate would also become a noted philanthropist, providing Johns Hopkins University with B&O stock worth more than 1 billion inflation-adjusted dollars.

He and his brother Henry learned the business from the ground up, as had their father, including how to tan leather from the teamster Alexander Sharp, how to salt pork and how to pack madder and Spanish whiting in barrels.

The Garrett company's initial fleet of Conestoga wagons carried food and supplies west over the old National Road, from Baltimore to Cumberland, Maryland and further to Ohio and the territorial capital at Vandalia, Illinois, or via the Ohio River toward the Mississippi River, or over the Cumberland Trail towards Kentucky and Tennessee.

With the end of the Mexican–American War of 1846–1848, they expanded toward the new American Southwest and California, causing the largest steamship then ever built in Baltimore, "The Monumental City", which soon made regular runs down the Chesapeake Bay to New Orleans, and San Francisco.

In 1854, the Baltimore City Council extended a five million dollars emergency loan to the struggling railroad's growing construction debt as the line pushed westward over the Appalachian Mountains.

The local newspaper The Sun on November 17, 1858, reported on the extensive debate and controversy between those directors wishing to keep the line in private hands, and those representing the interests of the state and city governments.

Following a motion by board member Johns Hopkins, (1795-1873), the largest stockholder since 1847 as well as chairman of the financial committee, Garrett became the B&O's new president.

Hopkins, a Maryland native, had become a hardware wholesale merchant on South Charles Street and made his substantial fortune in Baltimore.

[2] Federal troops with U.S. Marines led by Colonel Robert E. Lee, (U.S. Army), from Arlington House, Virginia across the river from the Capital, were sent to put down the rebellion on a special B&O train.

However, his business sense, with possibly political and economic acumen (and his anger at seeing Confederates tearing up his railroad) made him side with the Union and the policies of President Abraham Lincoln.

Under his direction, the B&O was instrumental in supporting the Federal government, as it was the main rail connection between Washington, D.C., and the northern and western states.

As battle preparations progressed, Garrett provided transport for Federal troops and munitions, and on two occasions President Lincoln contacted him directly for further information.

After the battle, President Lincoln commended Garrett as "The right arm of the Federal Government in the aid he rendered the authorities in preventing the Confederates from seizing Washington and securing its retention as the Capital of the Loyal States.

[10] Along with the B&O stock endowment, Hopkins had given his summer estate, Clifton, with the understanding that it would eventually become a permanent campus, once capital had been accumulated to commence a building program.

[13] As many well-to-do families moved to more spacious and luxurious residences, they acquired a semi-detached mansion in a neighborhood then known as "Garrett Park" near Franklin Square on the west side.

A later house fire resulted in the dramatic rescue of the two Garrett boys who were taken to the imposing nearby residence of Gen. George H. Steuart (militia general).

[14] In 1878 Garrett purchased and gave to his son, T. Harrison, "Evergreen" mansion off North Charles Street above Cold Spring Lane.

Garrett's daughter, Mary Elizabeth Garrett, (1854–1915), a civic activist, philanthropist in her own right and suffragist, helped found the Bryn Mawr School, the Baltimore Museum of Art, (1914), and secured the admission of women to the Johns Hopkins School of Medicine as a condition of her bequest to supplement the endowment of Hopkins' from twenty years before.

He died on September 26, 1884, at his summer home on the grounds of the Deer Park Hotel, which he, Senator Henry Gassaway Davis (a former B&O employee) and the B&O Railroad had developed in Garrett County, Maryland after the Civil War.

Nine years after the Great Baltimore Fire of February 1904, the firm marked the city's (and financial district's) revival by building a landmark skyscraper of thirteen stories (tall for those days) designed by noted architects J.B. Noel Wyatt and William G. Nolting in a variety of then popular styles including the Chicago, Commercial/Vernacular and Renaissance Revival styles at the southwest corner of Water and South Streets.