We took 105 oriented cores from 340 m of the upper Mauch Chunk Formation at Pottsville, Pennsylvania, for a magnetostratigraphic study. The samples were subjected to progressive thermal demagnetization from 600 to 700 °C and analyzed by using principal-components analysis. A high-temperature component was isolated with a mean direction of declination = 351.7°, inclination = -28.4°, and α95 = 6.7°, and a corresponding paleopole at long 113.5°E, lat 33.7°N. Three normal and three reversed polarity magnetozones were defined, and it was found that the magnetic field was ∼59% normal and 41% reversed in the upper Chesterian. Herein we attempt to correlate the section to a previous study in New Brunswick on the basis of the paleolatitude (pole position) and the reversal pattern, and we postulate a correlation of the bottom part of the Maringouin section with the top off the Mauch Chunk. Such a correlation would place the Mississippian/Pennsylvanian boundary within the Maringouin Formation. Earth's magnetic field was of normal polarity at the time of the Mississippian/Pennsylvanian boundary.