The Civil War was fast approaching though no one knew it. Map designs of the 1830's & 1840's were continued into this decade. Publishers would put out an atlas almost annually, but new maps were only added on an incremental basis so the same state map would appear in different atlases over several years.

Three new counties were created in this decade: Fulton (seat at McConnellsburg) in 1850, Montour (Danville) in 1850, and Snyder (Middleburg) in 1855. In 1854 the legislature passed the Act of Consolidation, providing that 'the city of Philadelphia, as limited by the charter of 1789, should be enlarged by taking in all the territory within the county of Philadelphia.' Thus, the county and city of Philadelphia became one political entity and the county government effectively disappeared.

	1850 A NEW MAP OF PENNSYLVANIA WITH ITS CANALS, RAILROADS &C., published by Thomas Cowperthwait & Co., 253 Market Street, Philadelphia, Pa. This map is probably from the 1850 (or slightly later) edition of Mitchell's A New Universal Atlas, now published by Cowperthwait. Blank verso. Scale: 1 inch = 23 miles. Size: 11 x 14 inches.
	1851 MIDDLE STATES, engraved by G.W. Boynton, and including Pennsylvania, New York, New Jersey, Delaware, and Maryland. It comes from a book published by Jenks, Hickling & Swan in 1851 or 1852, possibly S. G. Goodrich's Parley's First Book of History. It has 1850 population data above the title and a mileage table at the top. The engraver Boynton flourished circa 1850 and did work for Goodrich, Tanner, and others (per Lister). Blank verso. Scale: 1 inch = 100 miles. Size: 6.25 x 4.5 inches.
	1852 TOWNSHIP MAP OF PENNSYLVANIA, published by Horace Thayer & Co., 50 Ann St., New York and 127 Main Street, Buffalo. This is a traveler's pocket map that folds into a five by three inch reddish cardboard case with the title HORACE THAYER &CO.'S MAP OF PENNSYLVANIA. On the inside of the case is a list of other maps for sale by Thayer, Bridgman & Fanning, 156 William St., New York. The map has 1850 census data and dates 1850-55 by counties shown. Townships are indicated but are not differently colored. Rail lines and canals are shown, but not roads. The rail line west to Pittsburgh is shown as complete, which it was if the Portage Railroad was used. However, the main line through the Horseshoe Curve and Gallitzin tunnel did not open until 1854. Listed in Phillips, page 683. Longitude from Washington, blank verso. Scale: 1 inch = 13 miles. Size: 20 x 26.5 inches.
	1853 PENNSYLVANIA issued in 1853 by Ensign & Phelps, N. Y. The verso is page 286 with 1850 census data and the map can be dated 1850-55 by counties shown. A few rail lines and canals appear. The first locomotive chugged from Philadelphia all the way to Pittsburgh about this time. Longitude is from Washington. Scale: 1 inch = 40 miles. Size: 5.5 x 9 inches.
	1854 PENNSYLVANIA, published by J. H. Colton, No. 36 Cedar St., New York 1854. This map is on vellum paper and folds into a 5 x 3.5 inch black cover to which it is attached. On the inside of the cover is a Colton ad with a list of maps published. Like the Mitchells, two or three generations of Coltons were involved in map publishing. This is one of the famous pocket maps popular in the 19th century. Longitude is from Washington at the bottom, west from Greenwich at the top. The verso contains county census data. Scale: 1 inch = 22 miles. Size: 14 x 17 inches.
	1855 MAP OF THE PENNSYLVANIA RAIL ROAD FROM HARRISBURG TO PITTSBURG AND OF THE COLUMBIA & LANCASTER & HARRISBURG R.RS. FROM PHILADELPHIA TO HARRISBURG. H. Haupt, Chf. Eng., J. P. & J. Lesley Jr. Topographers, J. G. Shoemaker Engr., P. S. Duval & Co's Steam Lith. Press, Philada. This map comes from Guide for the Pennsylvania Railroad with an Extensive Map; including the Entire Route, with All Its Windings, Objects of Interest, and Information Useful to the Traveller, T. K. and P. G. Collins, Printers, Philadelphia 1855. It was apparently published by the railroad to advertise the just completed line to Pittsburgh. Only the title section , showing a portion around Lancaster, and a section approaching the Allegheny Front of this large strip map are shown here. This is one of the first maps published showing the entire line to Pittsburgh, reached in 1852 using the Portage Railroad, and in 1854 using the Horseshoe Curve and the Gallitzin Tunnel. The U-bend in the line just west of Altoona is the famous Horseshoe Curve. Blank verso. Scale: 1 inch = 4 miles. Size: 8.5 x 72 inches.
	1856 A NEW MAP OF THE STATE OF PENNSYLVANIA EXHIBITING ITS INTERNAL IMPROVEMENTS, ROADS DISTANCES &C. by J. H. Young, Philadelphia, published by Charles Desilver, 251 Market St. Entered according to act of Congress in the year 1856 by Charles Desilver...., this map is Plate 14 from an atlas published by Desilver in 1857. It can be dated 1855-60 by counties shown. Insets of Philadelphia and the coal regions of Lehigh and Schuylkill counties are included. Blank verso. Scale: 1 inch = 22 miles. Size: 14 x 17 inches.
	1857 PENNSYLVANIA, published in The Diamond Atlas with Descriptions of All Countries - the Western Hemisphere, by Charles Colby, editor of Morse's General Atlas of the World, Samuel N. Gaston, New York 1857. The map can be dated 1850-55 by the counties shown. Although the map is small, the townships within each county are delineated, and rail lines and canals shown. Blank verso. Scale: 1 inch = 60 miles. Size: 6 x 5 inches.
	1858 GEOLOGICAL MAP OF THE STATE OF PENNSYLVANIA, constructed from original surveys made between the years 1836 and 1857 under the superintendence of Henry D. Rogers, State Geologist. This is one of the iconic maps of Pennsylvania cartography, and the most important map of the latter 19th century. Henry Rogers was appointed state geologist at the age of 26 in 1836 and for the next twenty years, on and off depending upon funding, directed the first state geological survey publishing several annual reports. At the same time he contracted to study New Jersey geology, and published a geologic report on that state in 1840. In the 1850's he became a Professor at the University of Glasgow and while there published his two volume opus, The Geology of Pennsylvania. The illustrations (by George Lehman) and maps were engraved by W. & A. K. Johnston of Edinburgh, William Blackwood & Sons of Edinburgh printed the volumes, and J. B. Lippencott of Philadelphia was the American distributor. The volumes were accompanied by a map folio containing 7 maps: 2 (24 x 38 inch) black and white geological section maps, 2 (28 x 36 inch) color maps of the anthracite coal fields, and 3 (36 x 24 inch) color geological maps shown here of the eastern , middle , and western parts of the state. Pennsylvania has three major terrain zones: a coastal plain in the southeast and around Erie; mountain uplift also called 'ridge and valley' in the center and northeast; an eroded plateau in the west. For an interesting discussion of terrain features and geology, see Lobeck. These are among the earliest geological maps with lithographic color. In 1859, Rogers published a large political map of the state using the same initial plate as for these geological maps.
	1859 COLTON’S PENNSYLVANIA. Published by Johnson & Browning, 172 William St. New York. Entered according to Act of Congress in the year 1859 by J. H. Colton & Co. Just before the Civil War, A.J. Johnson took over, or acquired the rights to, a portion of Colton's business. The details of this are hazy now, Ristow(1985) discusses it briefly. Johnson then published an atlas in 1860; however, this was not the Pennsylvania map in that atlas. However it was used, this appears to be the first Pennsylvania map that appeared under the Johnson (& Browning) name although it is obviously a Colton map. Roads, railroads, and canals are shown. Blank verso; longitude west from Greenwich at top, from Washington at bottom. Scale: 1 inch = 21 miles. Size: 12.5 x 15.5 inches.