Two adjacent geodetic networks span a 105-km extent of the Wasatch fault zone in north-central Utah. One of the networks, located in the vicinity of Salt Lake City, was observed by the National, Ocean Service/National Geodetic Survey (NOS/NGS) in 1962--1963 (triangulation mode) and again in 1973--1974 (combined triangulation-trilateration mode). To the north, in the vicinity of Ogden, the U.S. Geological Survey (USGS) performed five separate trilateration surveys of the second network during the 1972--1981 interval. When fit to a model assuming both temporal and spatial homogeneity for the strain rate, the two independent data sets yield mutually consistent strain rate tensors. Subsets of the NOS/NGS data, however, suggest spatial variation in the strain field, and a subset of the USGS data indicates a possible temporal variation in the strain rate. The quality of the data is such that we are uncertain whether or not these apparent variations represent actual tectonic signals. The strain rate tensors for the two complete data sets suggest an underlying deformational pattern characterized by east-west (E-W) maximum principal strain (extension positive). This pattern may also be inferred from regional seismicity and Quaternary geology. The suspected variations would imply that the area to the north of Salt Lake City experienced significant E-W compression preceding 1978, in contradiction to the underlying strain pattern. This compression may be caused by the mountainous block, eastward adjacent to the fault zone, displacing westward along a shallow-angel, west dipping detachment surface. We speculate on the existence of an E-W trending zone of weakness, for example, secondary faults located north of Salt Lake City to explain how the stress field to the north may be decoupled from that to the south where E-W compression has not been detected. While seismic and geologic information contribute some plausibility to our speculations, the evidence for the existence of the suspected variations is inconclusive.