Depends on the state but here is
Alaska
Sec. 40.25.110. Public records open to inspection and copying; fees.
(a) Unless specifically provided otherwise, the public records of all public agencies are open to inspection by the public under reasonable rules during regular office hours. The public officer having the custody of public records shall give on request and payment of the fee established under this section or
AS 40.25.115 a certified copy of the public record.
Sec. 40.25.115. Electronic services and products.
(a) Notwithstanding
AS 40.25.110(b) — (d) to the contrary, upon request and payment of a fee established under (b) of this section, a public agency may provide electronic services and products involving public records to members of the public. A public agency is encouraged to make information available in usable electronic formats to the greatest extent feasible. The activities authorized under this section may not take priority over the primary responsibilities of a public agency.
(1) “electronic services and products” means computer-related services and products provided by a public agency, including
(G) generating maps or other standard or customized products from an electronic geographic information system;
They are allowed to restrict records of personal information, those having to do with security, or those that pertaining to trade secrets. I don't think unit boundaries fall into those categories.
Colorado has similar laws, while working for a state agency I had a number of requests come it where people asked for shapefiles, .kmz files, and maps. Depending on what was requested and/or how much time was required you could charge for the data, but you provided it. Mostly I provided subsidence data/aquifer maps.