Penn Valley is an unincorporated community located within Lower Merion Township, Pennsylvania, United States. Penn Valley residents share a zip code with Merion, Narberth, or Wynnewood because the community does not have its own post office. However, Penn Valley is a distinct community whose civic association demarcates its boundaries with iconic signs featuring William Penn and a farmhouse in blue or red on white, dating from 1930.
 Lower Merion was settled in 1682 by Welsh Quakers and in 1713 became a township with about fifty residents. Before 1930, what is now known as Penn Valley consisted of the areas of the township known as "Fairview," "Crow's Hill," and "Bowler's Woods."
 Initially, Penn Valley was a farming community, known especially for Percival Roberts's 539-acre dairy farm, "Penshurst," and the smaller farms that surrounded it, located on PA Route 23, Conshohocken State Road, Hagy's Ford Road, and Old Gulph Road. It grew more suburban in 1939 when Penshurst's 75-room mansion was demolished in favor of residential development. Other farms in Penn Valley included "Crow's Hill", which was sold in 1921; "The Grove of the Red Partridges" on Old Gulph Road; and Charles W. Latch's 41-acre family farm. Today, silos can still be found in Penn Valley on Fairview Road.
 Penshurst Farm was built and owned by Percival Roberts, scion of the Welsh family led by John Roberts that founded Lower Merion in 1682. Penshurst straddled Hagy's Ford Road and Conshohocken State Road and extended through the hollow down to the banks of the Schuylkill River. The 75-room mansion built in 1903 was known for its magnificent English gardens and Old World ornamental fountains, a fish pond, and a terraced stairway, elements of which still stand as components of the residence that was subsequently built upon the property. The original mansion generated its own electricity, and its plumbing system was self-sufficient.
 The dairy farm on the Penshurst property was one of the most productive in all of Pennsylvania, with modern milking machines and numerous barns. It had exquisite animals including a pack of award-winning Ayrshire cattle, which were known for eating alfalfa. The farm also had top-notch Berkshire hogs, chickens, and sheep. The farm likely had peacocks and pheasants because these remain common in Penn Valley. Penshurst milk was popular in the area because it was not pasteurized.
 In 1939 the mansion was demolished and the items were sold at an auction. Most of the land was sold in 1943 to Home Life Insurance Company, subdivided, and built upon. The farm's water storage tower persisted into the 1980s on a terrace between the baseball and football fields of Welsh Valley Middle School and gave its name to the adjacent Tower Lane. It, too, was ultimately demolished when state authorities deemed it a safety hazard.
 Today, the only remaining signs of the mansion are its former gates that can be seen as Conshohocken State Road bends left toward Gladwyne and Ardmore.
 Penn Valley is the home of the Penn Valley Women's Club, built by nearby farmers as a schoolhouse and Sunday meetinghouse in 1826–1828. 
The original club was replaced with a new building in 1876. Although that building was razed around 1926, its remains can be seen today set back from Fairview Road as it winds steeply down to Route 23. Until World War II, the Women's Club was used to hold religious services.
 The original Penn Valley Women's Club was repaired in 1951 and now is home to The Penn Valley Civic Association, the area's titular governing body. In 1978 this Women's Club was designated a historic site by the Pennsylvania Historical and Museum Commission. It was given repairs in 2016.
 Another historic building was located at the corner of Fairview Road and Summit Avenue, a small frame house with a Queen Porch built for the Centennial.  Even though the house had Class 2 Historical status, the township's Historical Committee allowed the house to be demolished after damage from a basement fire proved too costly to repair. The original house was demolished in August 2013 and a new house completed on the site late in 2014.

 During the period of the American Revolution, Benjamin Franklin, who was the United States Postmaster General, insisted on having stone milestone markers to keep postal riders on schedule. In 1793 the Mutual Assurance Fire Company of Philadelphia erected milestones to honor William Penn's family in return for its donation of land. Milestones 9 through 13 distant from the center of Penn's downtown grid were set within Penn Valley's limits. They have a mile number on their front and Penn's family coat of arms on the back.
 The Mill Creek passes through Penn Valley on its way to the Schuylkill River. During the late 17th and early 18th centuries, 24 stone mills were located along the creek, which used its water power to process wool, paper, and gunpowder until early in the twentieth century. One mill owner, John Frederick Bicking, owned a paper mill along Mill Creek and ten acres where Summit Road meets Fairview Road. The Bickings family cemetery can still be found on Fairview Road.
 The 2010 Census found that Penn Valley has less than 4,000 residents. Racially, 88% of Penn Valley's residents are Caucasian, 4% are Asian, 2.4% are Hispanic, 1.8% are black and the rest are two or more races, Pacific Islander, American Indian or another race. Of Penn Valley's Caucasian residents, 14.7% have Russian ancestry and 4.0% have Eastern European ancestry.
 Penn Valley's median income is more than $100,000 per family, statistically in the top 0.3% of the United States. None of the children in the community live below the poverty level.
 Penn Valley is located between Merion and Gladwyne in the heart of the northern tier of communities belonging to the Philadelphia Main Line, a part of suburban Philadelphia named after the Pennsylvania Railroad's original rail line to the West. The railroad runs from 30th Street Station in downtown Philadelphia due west through the communities of Overbrook, Merion, Narberth/Penn Valley, Wynnewood, Ardmore, Haverford, Bryn Mawr, Rosemont, Villanova, Wayne, Strafford, Saint Davids, Devon, Berwyn, Daylesford, and Paoli.
 Most of Penn Valley is residential, except for parts of Montgomery Avenue, which separates the western part of Penn Valley from the borough of Narberth, its post office cousin.
 Penn Valley is only a valley in some places. The Merion part of Penn Valley slopes steeply down General Lafayette Road and Woodbine Avenue to Gulley Run Creek, a tributary of Mill Creek; Hollow Road slopes more gradually down toward the Schuylkill River and an east-only entrance to the Schuylkill Expressway into an old ravine that ends in the river; and Conshohocken State Road/PA Route 23 slopes steeply from the gates of the former Penshurst Estate down to a hollow where it meets Mill Creek Road and bends in a 90-degree angle toward the steep slope that leads into the village of Gladwyne.
 The highest point in Penn Valley is on the ridge above the playing fields of Welsh Valley Middle School, from which the tallest skyscrapers of Center City Philadelphia may easily be seen. Elevation at that point is 380 feet above Hagy's Ford Road.
 Lower Merion Township maintains its recycling and refuse burning center at the foot of Woodbine Avenue in Penn Valley, just beyond the limits of Belmont Hills, the easternmost section of the township that slopes down to the Schuylkill River, flanked by Fairmount Park.
 Police and public works are managed in the Lower Merion Township Office Building at 75 East Montgomery Avenue in Ardmore.
 Penn Valley is served admirably by the Lower Merion School District, headquartered at the bend of Montgomery Avenue in Ardmore where it meets Church Road, across from Lower Merion High School's Hap Arnold Field.
 The Narberth train station is located a scant mile from the "business district" of Penn Valley on Montgomery Avenue; Merion and Ardmore stations are roughly three miles to the east and west of the district, respectively.  All three have heated, enclosed waiting areas, public restrooms, and pay phones. Taxi service is summoned by telephone. Approximately 10% of Penn Valley's residents take the train to work.
 SEPTA's 121 and 44 lines run through Penn Valley between Center City and Gladwyne, Pennsylvania, on weekdays.
 Both Bryn Mawr and Lankenau Hospital are located within 5 miles of Penn Valley.
 Penn Valley is well served by the large and well-endowed Lower Merion Library System, part of the Montgomery County Library System and an affiliate of the numerous excellent academic and professional libraries in Philadelphia and its suburbs. The Lower Merion Library System just renovated (2012) its Narberth Free Library, bordering Narberth Field on Essex Avenue; its Ardmore Free Library on Ardmore Avenue just south of the US Post Office (2013); and the system's central Ludington Memorial Library of Bryn Mawr at the corner of Bryn Mawr Avenue and Lancaster Avenue (Route 30) (2014). Other excellent Lower Merion libraries just a short drive from Penn Valley include the Gladwyne Free Library in the village; the Bala-Cynwyd Library on Old Lancaster Road less than a mile from 54th and City Line Avenue; and the Penn Wynne Library south of Lancaster Pike. Residents of Lower Merion have free access to all of the libraries in the system. All of the libraries have a large variety of books, audio-visual materials, and electronic resources.
 Penn Valley has its own Little Free Library, which is a wooden box located on Hagys Ford Road between Margo Lane and Righters Mill Road. One must follow a certain procedure: In return for taking the book you want from the wooden box, you deposit another in its place.
 The two closest Fire Departments are The Gladwyne Fire Station where Route 23 meets Rock Hill Road and The Narberth Fire Station on Haverford Avenue just above Narberth Park. The Gladwyne Fire Station's mascot is a dalmatian named Rowdy.
 Before Welsh development, Penn Valley's forest was home to bears, cougars, wolves, rattlesnakes, otters, beavers, weasels, turkeys, grouses, woodland bison, trout, and bald eagles. However, after forest destruction by the Welsh and home building after World War II, most of the rarer animals left.
 Today, the area is filled with squirrels, chipmunks, rabbits, white-footed mice, horned owls, red-tailed hawks, red foxes, opossums, skunks, raccoons, woodchucks, pheasants, songbirds, crayfish, butterflies, and white-tailed deer.
 White-tailed deer occasionally pose a problem in Penn Valley. They can halt traffic, destroy the forest underbrush, devour expensive ornamental flowers, and spread Lyme disease.  When last counted, Penn Valley harbored 44 deer per square mile, 34 more than the recommended average.
 A coyote was spotted just outside of Penn Valley in 2017.
 Penn Valley's residents primarily speak English. However, 3.5% of the residents primarily speak French.
 Nearly all of Penn Valley's public school children attend Penn Valley Elementary School and Welsh Valley Middle School, which are part of Lower Merion School District. Children and their parents may choose between attending Lower Merion High School or Harriton High School. Nearby private schools include Narberth's Roman Catholic St. Margaret's School; the all-male Haverford School; the all-female Baldwin School and Agnes Irwin Schools; and the co-educational Shipley School.
 While no colleges are located directly in Penn Valley, many campuses are nearby. Saint Joseph's University is no more than ten minutes away, with parts of its campus located in Merion and Bala-Cynwyd; and Villanova University, with its main campus along Lancaster Avenue/US Route 30 just west of Bryn Mawr. Other nearby colleges include Rosemont College; Haverford College; and the internationally renowned Bryn Mawr College
 In the state legislature, Penn Valley lies within the boundaries of the 148th District and is currently represented by Mary Jo Daley; Amanda Cappelletti is its Pennsylvania Senator. In the U.S. Congress, Penn Valley is represented by Madeleine Dean. In the 2020 Election, Lower Merion voted 78% for Joe Biden and 20% for Donald Trump.
 Penn Valley does not have a mayor or city council. However, it is represented in the Lower Merion Ward of Commissioners by Daniel Bernheim and Joshua Grimes.
 Local events are covered by The Main Line Times newspaper; Main Line Life monthly magazine; Philadelphia magazine; and The Philadelphia Inquirer. Over the air waves KYW Newsradio 1060 AM follows events in the city and suburbs by the minute and local television stations KYW-TV (CBS 3), WCAU (Channel 10), WPVI-TV (6 ABC), WPHL-TV (PHL17), and WTXF-TV (FOX 29) broadcast news and entertainment 24 hours a day.
 Penn Valley tends to have hot, humid summers and cold, snowy winters. Precipitation in Penn Valley tends to be higher than the national average as well as higher than in Center City Philadelphia, thanks to its ubiquitous woods, proximity to water, and elevation above the riverbanks.
 No recorded major natural disaster has ever taken place in Penn Valley. However, major natural disasters have taken place nearby. In the summer of 1972, torrential rains caused the Schuylkill River to rise well above its banks, flooding Belmont Hills south of the river and Manayunk north of it. In 1994 a 4.6 '"`UNIQ--templatestyles-00000021-QINU`"'mb earthquake took place 46 miles from Penn Valley, with a maximum Mercalli intensity of V (Moderate), causing some damage in the Reading area.
 In both 1994 and 1995, tornadoes took place within 20 miles of Penn Valley, resulting in four deaths and causing millions of dollars of property damage.