The Allegheny Front
Almost everything about Altoona's history comes back to one piece of geography: the mountain wall immediately to its west. Geologists call it the Allegheny Front. The National Park Service's geodiversity atlas for the Allegheny Portage Railroad National Historic Site describes it as a sharp escarpment, a long, steep step in the land, that divides two of the great regions geologists use to describe the eastern United States: the Appalachian Plateaus to the west and the Valley and Ridge province to the east.
The atlas gives its scale. The front runs from northern Pennsylvania into southeastern West Virginia, about 174 miles in all, with roughly 2,000 feet of elevation change overall. The background essay for the Pennsylvania Historical and Museum Commission (PHMC) marker titled "Altoona" calls it a 2,300-foot-high ridge. The figures measure slightly different things, but they agree on the main point: for anyone travelling west, the front was a wall.
The atlas states plainly that the Allegheny Front was an imposing barrier to east-west trade and travel, and that it was the reason the Allegheny Portage Railroad was built. The same barrier is why the Pennsylvania Railroad put its shops, and therefore a town, at its foot. The Portage Railroad and Horseshoe Curve pages tell those stories.
Two kinds of country
The two sides of the front look and are built differently, and the atlas explains why. East of the front, where Altoona lies, the land is a series of rounded, linear hills cut by narrow valleys, stepping up toward the top of the escarpment. The rocks there are strongly folded, faulted and deformed, the result of the mountain-building episode geologists call the Alleghenian orogeny.
West of the front the country changes. The hills undulate and slope gently away from the escarpment, and the rocks lie in nearly flat layers, much as they were first deposited. The main rock types of the front itself are sandstone (with some conglomerate), siltstone and shale.
The atlas lists several named features associated with the front in Pennsylvania, including Blue Knob, Horse Shoe Curve and Wopsononock Lookout. It also notes, for the park, the ordinary hazards of steep slopes in this kind of rock: landslides, slumping and rockfalls where weak shale lies under harder sandstone.
Worked example
This is an illustration of the atlas's description, not a geological survey of any site. Picture a traveller heading west from Harrisburg. For most of the trip the route follows valleys between long, parallel ridges, the folded country of the Valley and Ridge. At Altoona the ridges end against a single steep rise. Above it, at the summit near Gallitzin, the land opens into rolling upland on flat-lying rock. The PHMC essay puts the summit at 2,161 feet above sea level.
The valley the city fills
The Historic American Buildings Survey (HABS) report on Altoona, held by the Library of Congress, places the city in a wide valley on the eastern side of the Allegheny Mountains and notes its old nickname, the "mountain city". The valley was the Logan Valley, mostly farmland and woods when the railroad arrived in 1849.
The railroad shaped the valley floor. HABS describes the tracks and shops running along the centre of the valley and dividing the city, with houses set in rows and steps up the hillsides on either side. East of the city lies Pleasant Valley; on the East Side, Prospect Hill rises above the old neighbourhoods. Early visitors, the report says, remarked on the contrast between the mountain setting and a town darkened by coal smoke from the shops.
Water and the divide
The crest of the mountain west of Altoona also divides two great river systems. The geodiversity atlas places the main unit of the Portage Railroad site on the divide between the Chesapeake Bay watershed to the east and the Ohio River basin to the west. Blair Gap Run, it says, flows from Cresson Summit toward the Juniata River.
Altoona's own water history follows the same slope. HABS records that when the city planned its sewers in the 1880s, it divided the city into four districts following natural drainage, and the three northern districts drained into the Juniata River. The city's reservoirs were built in the mountain folds at Kittanning Point, inside the bend of Horseshoe Curve.
The city in measurements
Two US Census Bureau files give the plainest modern facts about the city's size. The Bureau's 2020 gazetteer of places in Pennsylvania lists Altoona city with a land area of 9.791 square miles and an internal reference point at about latitude 40.51 north, longitude 78.40 west.
| Measure | Altoona city | Blair County |
|---|---|---|
| Land area (2020 gazetteer) | 9.791 sq mi | Not used on this site |
| Population, April 1, 2020 (estimates base) | 43,951 | 122,821 |
| Population estimate, July 1, 2024 | 42,719 | 120,269 |
The population figures come from the Census Bureau's Population Estimates Program. On those figures, about 36 percent of the county's people lived in the city in 2020. Estimates are revised each year; the Census Bureau's own tables are the authority for current numbers.
Blair County
Altoona lies in Blair County. The Pennsylvania State Archives' table of county courthouses records that the county was formed on February 26, 1846, from parts of Huntingdon and Bedford Counties, and that its county seat is Hollidaysburg, not Altoona. That makes the county older than the city: it was created three years before the railroad laid out the town.
The county's early history is tied to the same transport routes as the city's. Hollidaysburg was the eastern end of the Allegheny Portage Railroad, where the canal basin met the railroad over the mountain, according to the National Park Service.
Places around the city
The city's boundary has moved over time. HABS records a large annexation in January 1929, 4.57 square miles that more than doubled the city's area and added about 17,000 people. It brought in Juniata, Fairlawn and Wehnwood to the north, the East End and Collinsville to the east, and a group of Logan Township developments to the west and south, among them Locust Hills, Eldorado, South Altoona, Llyswen and Lakemont Terrace.
Some names in the area are older than Altoona itself. HABS notes that Collinsville, in Pleasant Valley, predates the city, and that Eldorado took its name from a post office opened after the California gold discovery of 1848. The civic history page explains what annexation meant for city services.
The story continues: Local government and civic history