Philadelphia and Montgomery counties PA 309 begins at an interchange between
PA 611 (
Old York Road) and
Cheltenham Avenue on the border between the
East Oak Lane section of
Philadelphia in
Philadelphia County to the south and
Cheltenham Township in
Montgomery County to the north. From this interchange, the route heads northwest on four-lane
divided Cheltenham Avenue along the border between Philadelphia and Cheltenham Township. A short distance from the PA 611 interchange, the road comes to an intersection with the northern terminus of
Broad Street. PA 309 continues northwest as a four-lane undivided road through urban residential and business areas, passing to the north of
Northwood Cemetery. The road crosses Washington Lane and heads to the south of
Greenleaf at Cheltenham shopping center before it comes to an intersection with Ogontz Avenue north of the
West Oak Lane section of Philadelphia, with
SEPTA's Cheltenham-Ogontz Bus Loop located on the northwest corner of the intersection. At this point, PA 309 turns north-northwest onto four-lane divided Ogontz Avenue and fully enters Cheltenham Township in Montgomery County, passing businesses as it heads to the west of the shopping center. The route intersects Limekiln Pike and assumes that name, running near suburban residential areas in
Cedarbrook. Past this intersection, the route transitions into a five-lane road with a center left-turn lane and runs north past more businesses with some wooded residential development, bending northwest. The road enters
Hatfield Township and reaches
Colmar, where it intersects Broad Street and crosses SEPTA's Lansdale/Doylestown Line at-grade to the west of
Colmar station. PA 309 continues past commercial development, crossing the
West Branch Neshaminy Creek and passing through Trewigtown.
Bucks County PA 309 leaves the North Penn Valley region and becomes a four-lane freeway called the Sellersville Bypass, coming to a partial interchange with Bethlehem Pike that has a northbound exit and a southbound exit and entrance in addition to a southbound
right-in/right-out with Bergey Road. At this point, the route curves north-northwest to fully enter Hilltown Township in Bucks County. The freeway runs through wooded areas with nearby residential and commercial development and comes to a diamond interchange with
PA 113 northeast of
Souderton. PA 309 turns north and runs through woodland and farmland with some nearby development, curving northwest and crossing into
West Rockhill Township. The route passes over the
Bethlehem Line, a railroad line that is owned by SEPTA and operated by the
East Penn Railroad, and reaches a diamond interchange with the northern terminus of PA 152 that provides access to
Sellersville to the northeast and
Telford to the southwest. Past this interchange, the freeway heads through wooded areas and crosses the
East Branch Perkiomen Creek before it passes near farmland and curves north. PA 309 runs through woodland with some farm fields and comes to a diamond interchange at Lawn Avenue, which heads west to provide access to
PA 563 west of
Perkasie, before passing under PA 563. From here, the route heads near more farms and woods and curves northwest, running through dense forests and bending north. PA 309 comes to a southbound exit and northbound entrance with Bethlehem Pike, at which point the Sellersville Bypass freeway ends. Past this intersection, PA 309 becomes a four-lane freeway and comes to an interchange with
I-78 and the southern terminus of
PA 145 in
Lanark. At this point, PA 309 heads west concurrent with I-78 westbound on a six-lane freeway, while PA 145 northbound provides access to
Allentown. The highway comes to a southbound exit and northbound entrance with Rock Road that provides a connection to PA 145 in
Summit Lawn, at which point it crosses into
Salisbury Township. Following this, I-78/PA 309 descends forested
South Mountain. After crossing the mountain, the freeway heads into Allentown and passes near neighborhoods, coming to a northbound exit ramp serving Emaus Avenue. The highway runs near industrial areas and passes over Norfolk Southern's
Reading Line before it comes to a
partial cloverleaf interchange at
Lehigh Street. I-78/PA 309 heads south of
Allentown Queen City Municipal Airport and runs near residential areas before running through woodland, passing through a small section of Salisbury Township before heading back into Allentown and crossing
Little Lehigh Creek. The freeway heads back into Salisbury Township and runs between residential areas to the north and office buildings to the south before reaching a partial cloverleaf interchange with the northern terminus of the southern section of
PA 29 at
Cedar Crest Boulevard. Past this interchange, the highway heads north of
Lehigh Valley Hospital–Cedar Crest and crosses into
South Whitehall Township, passing between residential areas to the north and farm fields to the south and curving northwest to come to a partial cloverleaf interchange with the northern terminus of
US 222 and the southern terminus of
PA 222 at Hamilton Boulevard, which provides access to Allentown and
Reading. From here, the freeway enters
Lower Macungie Township and runs past commercial development to the southwest of the
Dorney Park & Wildwater Kingdom amusement park. PA 309 splits from I-78 at a partial interchange and continues north along a four-lane freeway, passing through a small corner of
Upper Macungie Township before entering South Whitehall Township again. The route continues north past farmland with some residential and commercial development and comes to a cloverleaf interchange at
Tilghman Street. The freeway runs northwest near more homes and commercial establishments and reaches a cloverleaf interchange with the
US 22 freeway a short distance east of that route's interchange with the
Pennsylvania Turnpike Northeast Extension, also known as
I-476. Past this intersection, the route splits into a one-way pair along Mauch Chunk Street northbound and North Railroad Street southbound, running to the east of the Reading Blue Mountain and Northern Railroad's
Reading Division line and passing east of the former
Tamaqua station along the railroad line. The one-way pair carries one lane in each direction. Northbound PA 309 shifts to Pine Street and the route continues to follow the one-way streets past residences and a few businesses. Both directions of PA 309 rejoin along an unnamed three-lane road with a center left-turn lane and crosses the Little Schuylkill River, heading into forested areas to the east of the river and to the west of
Nesquehoning Mountain and curving northwest. The route leaves Tamaqua for
Rush Township and the name changes to Claremont Avenue, becoming a three-lane road with two northbound lanes and one southbound lane and curving to the north away from the Little Schuylkill River. The road heads into
Hometown and runs near homes and a few businesses, curving northwest and coming to an intersection with
PA 54. From here, PA 309 widens into a four-lane divided highway and heads past businesses. The route comes to a bridge over the Reading Blue Mountain and Northern Railroad's Reading Division line and runs through wooded areas and commercial development. The road runs through forests and curves north, passing to the west of Broad Mountain. PA 309 bends to the north-northwest and passes through Still Creek and Ginther. The route heads back into wooded areas and crosses into
Kline Township, curving to the northeast and north along Mile Hill Road. The road runs north-northeast and passes to the west of a large coal mine before it comes to a
trumpet interchange with a ramp providing access to
I-81 to the west. Past this interchange, PA 309 heads through forests with some development before passing under a Reading Blue Mountain and Northern Railroad line and entering
McAdoo. Here, the route becomes South Kennedy Drive and narrows to a two-lane undivided road, running past homes and a few businesses. The road crosses Blaine Street in the center of McAdoo, where its name changes to North Kennedy Drive, passing more residences. PA 309 leaves McAdoo and heads through a small section of Kline Township.
Luzerne and Wyoming counties PA 309 heads into
Hazle Township in
Luzerne County, which is in the
Wyoming Valley region, and becomes South Church Street. The route runs past coal mines and widens to four lanes, curving to the north. The road passes through wooded areas with some homes and businesses and comes to an intersection with
PA 424, where it briefly turns into a divided highway. Past this intersection, the route becomes undivided again and crosses Norfolk Southern's Sheppton Industrial Track at-grade, heading past homes and commercial buildings and curving northeast into
Hazleton. PA 309 runs through commercial areas and woodland, narrowing to two lanes. The road passes under Norfolk Southern's Hazleton Running Track and runs through residential areas before passing businesses and becoming a three-lane road with a center turn lane. The route crosses the Hazleton Running Track at-grade and passes west of the Church Street Station serving
HPT buses as it heads into the downtown area of Hazleton, where it reaches a junction with
PA 93. Past this junction, PA 309 becomes two-lane North Church Street and leaves the downtown to head past homes. The road curves to the north at the Diamond Avenue intersection and continues through residential areas, gaining a center left-turn lane coming to an intersection with the northern terminus of
PA 924. The route runs through more of Hazelton and passes businesses as it reaches a junction with the western terminus of
PA 940 on the northern border of Hazelton. At this point, PA 309 crosses back into Hazle Township and runs through commercial areas as an unnamed road, passing to the west of Church Hill Mall and widening to five lanes. The road runs to the east of
Hazleton Municipal Airport and heads past residences and businesses in
Milnesville, briefly becoming a four-lane divided highway at the Airport Beltway/Louis Schiavo Drive intersection. The route turns into an undivided road again and runs through wooded areas with some homes, passing to the west of a coal mine and curving northeast. PA 309 enters
Butler Township and becomes South Hunter Highway, heading through forested areas as it traverses Buck Mountain as a two-lane road and gaining a second southbound lane as it descends the mountain. The route turns to the north and crosses
Little Nescopeck Creek, running through a mix of fields, woods, and development as a two-lane road briefly before becoming four lanes. The road heads northeast and runs through forests to the west of Green Mountain, narrowing to two lanes before becoming three lanes with two southbound lanes and one northbound lane. PA 309 bends to the north again and becomes four-lane undivided North Hunter Highway, running through wooded areas with some homes and businesses. The road crosses
Nescopeck Creek and passes through Honey Hole and Edgewood. The route becomes a divided highway and comes to a diamond interchange with
I-80. Past this interchange, PA 309 becomes a three-lane undivided road with two northbound lanes and one southbound lane and runs through wooded areas with some residences and commercial establishments, passing by the entrance of Sand Springs. The road curves to the north-northeast and traverses forested
Nescopeck Mountain, widening to four lanes as it comes to the summit in
Nescopeck Pass and bends north. The route heads into
Dorrance Township and becomes South Mountain Boulevard, heading northeast to descend Nescopeck Mountain with one northbound lane and two southbound lanes. PA 309 switches to two northbound lanes and one southbound lane and heads into
Wright Township, becoming a three-lane road with a center turn lane as it passes near wooded residential development and runs through Konns Corners. The road runs through forests with some commercial development, passing east of
Crestwood High School and crossing
Bow Creek before entering
Fairview Township. The route heads near homes and businesses in Fairview Heights, becoming North Mountain Boulevard and widening to five lanes. PA 309 narrows back to three lanes and crosses
Big Wapwallopen Creek before it heads through
Mountain Top, curving to the northwest and coming to an intersection with the northern terminus of
PA 437 in Fairview. The road runs through forested areas as it passes through Solomon Gap in
Penobscot Mountain, narrowing to two lanes before turning into a four-lane divided highway. The route curves north and crosses
Solomon Creek as it enters
Hanover Township, with the median widening as it continues to wind north through the gap in the mountain east of the creek. The median narrows and PA 309 crosses
Pine Creek as it continues northwest, passing southwest of a section of the
Pinchot State Forest. == History ==