1840 January 0
Pittsburgh developed as a coal port; in this year coal shipments out of city totaled 464,826 tons.

1840 January 0
Peter Duff's Mercantile College (Duff's Business College) established.

1840 January 0
Population: 21,515; Allegheny City, 10,089; Allegheny County, 81,235.

1840 April 13
Allegheny was incorporated as a third-class city with a population of 10,989.

1840 May 4
Clayton's "aerial mail packet" balloon, bound for Philadelphia, took off from Pittsburgh and landed the same evening in the vicinity of Tarentum.

1840 July 17
William Robinson was inaugurated as first mayor of Allegheny City.

1841 January 0
En route to Washington for his inauguration, President-elect William H. Harrison visited the city.

1841 April 0
The hostelry Monongahela House, opened its doors.

1841 July 31
A strike followed by riots in six cotton factories in Allegheny. September 8: The Pittsburgh Weekly Chronicle began publication.

1842 January 0
The second courthouse, designed by John Chislett, was completed on Grant's Hill.

1842 March 20
Charles Dickens, the English author, arrived with his wife at the Exchange Hotel, Penn Avenue at Sixth, for a three-day visit.

1842 September 10
Pittsburgh Daily Morning Post was first published. The Henry Oliver family, including 2-year-old Henry William Oliver, emigrated from Ireland to Pittsburgh.

1843 January 0
The Aqueduct was rebuilt on the suspension principle, using wire cable made by John Roebling. This was the first great public work in which wire cable was used in place of wooden beams.

1843 August 7
The See of Pittsburgh was created with the Right Reverend Michael O'Connor as first bishop.

1843 December 22
Seven Sisters of Mercy arrived from Ireland to establish their Order here.