A level 3 (L3) sparse network almanac (SNA) is generated using data from a base station almanac with information for a plurality of base stations. The information for base stations includes cell identifiers that include an L3 region code that is one layer above a cell tower identification level. Cell boundaries are determined from the base station information. The cell boundaries are used to estimate a region of coverage for the L3 SNA, which may be stored in a database. For example, region points may be generated from the cell boundaries, and used to estimate the region of coverage for the L3 SNA. The region of coverage may be determined, e.g., as a minimum enclosing circle or other similar techniques. The larger of an estimated region size parameter, e.g., a radius of a circle, and a default size may be used for the region of coverage.