The Bureau of Mines, Helium Field Operations, in Amarillo, Texas, has determined the helium 4 content of near-surface atmospheric air within the continental United States. Analysis of 40 atmospheric samples obtained from 12 locations during a 1-year period showed the helium 4 content of dry air to be constant at 5.2204¿0.0041 ppm by volume (ppmv). The reported accuracy of ¿0.0041 ppm is at the 68% confidence level. The mean helium concentration obtained is in agreement with the concentration of 5.222¿0.017 ppmv reported by Oliver et al. (1984) but is 0.36¿0.08% lower than the currently accepted value of 5.239¿0.004 ppm reported by Glueckauf (1946). A helium-4-tuned mass spectrometer having a precision of ¿0.0011 ppm was used to analyze the air samples. Helium-4-in-nitrogen gravimetrics standards accurate to ¿0.003 ppm were used for calibration of the mass spectrometer.