Like most members of the white pine group, Pinus subgenus Strobus, the leaves ("needles") are coniferous, occurring in fascicles (bundles) of 5, or rarely 3 or 4, with a deciduous sheath. The leaves are flexible, bluish-green, finely serrated, and 5–13 cm (2–5 in) long. The fascicle sheaths persist for 18 months, i.e., from the spring of one season until autumn of the next, when they abscise.
The seed cones are slender, 8–16 cm (3+1⁄4–6+1⁄4 in) long (rarely longer than that) and 4–5 cm (1+1⁄2–2 in) broad when open, and have scales with a rounded apex and slightly reflexed tip, often resinous. The seeds are 4–5 mm (5⁄32–3⁄16 in) long, with a slender 15–20 mm (5⁄8–3⁄4 in) wing, and are dispersed by wind. Cone production peaks every 3 to 5 years.
The branches are spaced about every 18 inches on the trunk with 5-6 branches appearing like spokes on a wagon wheel.
Eastern white pine is self-fertile, but seeds produced this way tend to result in weak, stunted, and malformed seedlings.
Mature trees are often 200–250 years old, and some live to over 400 years. A tree growing near Syracuse, New York was dated to 458 years old in the late 1980s and trees in Michigan and Wisconsin were dated to approximately 500 years old.
The eastern white pine has the distinction of being the tallest tree in eastern North America. In natural pre-colonial stands it is reported to have grown as tall as 70 m (230 ft). There is no means of accurately documenting the height of trees from these times, but eastern white pine may have reached this height on rare occasions. Even greater heights have been reported in popular, but unverifiable, accounts such as Robert Pike's "Tall Trees, Tough Men".
Total trunk volumes of the largest specimens are approximately 28 m3 (990 cu ft), with some past giants possibly reaching 37 or 40 m3 (1,300 or 1,400 cu ft). Photographic analysis of giants suggests volumes closer to 34 m3 (1,200 cu ft).
Pinus strobus grows approximately 1 m (3.3 ft) annually between the ages of 15 and 45 years, with slower height increments before and after that age range. The tallest presently living specimens are 50–57.55 m (164 ft 1 in–188 ft 10 in) tall, as determined by the Native Tree Society (NTS). Prior to their exploitation, it was common for white pines in northern Wisconsin to reach heights of over 200 ft (61 m). Three locations in southeastern United States and one site in northeastern United States have trees that are 55 m (180 ft) tall.
The southern Appalachian Mountains have the most locations and the tallest trees in the present range of Pinus strobus. One survivor is a specimen known as the "Boogerman Pine" in the Cataloochee Valley of Great Smoky Mountains National Park. At 57.55 m (188 ft 10 in) tall, it is the tallest accurately measured tree in North America east of the Rocky Mountains. It has been climbed and measured by tape drop by the Native Tree Society. Before Hurricane Opal broke its top in October 1995, Boogerman Pine was 63 m (207 ft) tall, as determined by Will Blozan and Robert Leverett using ground-based measurements.
The tallest specimens in Hartwick Pines State Park in Michigan are 45–48 m (148–157 ft) tall.
In northeastern USA, 8 sites in 4 states currently have trees over 48 m (157 ft) tall, as confirmed by the Native Tree Society. The Cook Forest State Park of Pennsylvania has the most numerous collection of 45 m (148 ft) eastern white pines in the Northeast, with 110 trees measuring that height or more. The Park's "Longfellow Pine" is the tallest presently living eastern white pine in the Northeast, at 55.96 m (183 ft 7 in) tall, as determined by being climbed and measured by tape drop. The Mohawk Trail State Forest of Massachusetts has 83 trees measuring 45 m (148 ft) or more tall, of which 6 exceed 48.8 m (160 ft). The "Jake Swamp Tree" located there is 51.54 m (169 ft 1 in) tall. The Native Tree Society maintains precise measurements of it. A private property in Claremont, New Hampshire has approximately 60 specimens that are 45 m (148 ft) tall.
Diameters of the larger pines range from 1.0–1.6 m (3 ft 3 in–5 ft 3 in), which translates to a circumference (girth) range of 3.1–5.0 m (10 ft 2 in–16 ft 5 in). However, single-trunked white pines in both the Northeast and Southeast with diameters over 1.45 m (4 ft 9 in) are exceedingly rare. Notable big pine sites of 40 ha (99 acres) or less will often have no more than 2 or 3 trees in the 1.2 to 1.4 m (3 ft 11 in to 4 ft 7 in) diameter class.
Unconfirmed reports from the colonial era gave diameters of virgin white pines of up to 2.4 m (8 ft).