How many minutes can a section line depart from a cardinal direction and still be considered regular?

In surveying, especially with respect to land platting and the orientation of section lines, a section line can generally deviate from the cardinal directions (north, south, east, west) by a specific angle while still being categorized as "regular." A standard deviation that is often recognized is 21 minutes. This amount has been established in practice to ensure that the integrity of a rectangular survey system is maintained, while still allowing for minor adjustments due to physical terrain or other practical considerations.

The other options present larger deviations from the cardinal directions. For instance, if a section line were to depart by 30 minutes or more, it may begin to distort the intended layout of sections and townships defined by the Public Land Survey System. Thus, while a small degree of deviation is acceptable, moving beyond the established threshold compromises the defining parameters necessary for maintaining regularity in the survey's layout. This balance is particularly important in ensuring that there is uniformity and clarity in land delineation.