Detailed paleomagnetic records from the wet sediments of two Minnesota lakes are the basis for estimating the local secular variation of the earth's magnetic field during late Quaternary time. Results from Lake St. Croix cover the interval 0--9500 years B.P., and results from Kylen Lake cver the interval 4000--14,000 years B.P. Paleomagnetic data were recovered from two replicate cores in each lake by sampling the sediments at 3- to 10-cm intervals. Analysis of the potential errors in the results indicates that all cores were correctly oriented in the vertical plane but that some azimuthal offsets of individual core segments did occur. Various methods for correcting the occasional azimuthal offsets are described. The final paleomagnetic data sets from each lake show a high degree of internal consistency. These results also show close correspondence (1) between the two lakes, (2) with the known historic magnetic field variation, and (3) with paleomagnetic results from data archeological material and lava flows from the western United States. Rock magnetic analysis of the lake sediments indicates that the natural remanent magnetization is the result of a physiccal remanence acquisition process (detrital remanent magnetization) active at or near the sediment/water interface. There is no evidence for a systematic inclination error in the results. Statistical analysis of vector time series determined from the paleomagnetic data indicates that both the field-vector and virtual geomagnetic pole (VGP) distributions are non-Fisherian and essentially axial-dipolar when averaged over 10,000 years. Spectral analysis of the scalar inclination and declination suggests that the field behavior is separable into a dominant low-frequency dipolelike waveform (period of -9500 years) and a higher-frequency band irregular waveform (''fundamental'' period of -2400 years with multiples at 1200, 800, and 600 years) that may represent the nondipole field. This irregular waveform is interpreted as resulting from zonal drift of the nondipole field past Minnesota on the basis of waveform morphology and VGP circularity. Zonal drift of the nondipole field plus a low-frequency dipole variation can account for almost all of the observed paleomagnetic field variation.