San Francisco-based Gap Inc. is closing about 175 of its namesake units, or 25 percent of its total North America store count, after major sales declines.

The retailer, which also owns Old Navy and Banana Republic, is also laying off about 250 employees in its San Francisco and New York City office operations.

After the store closings, it will be left with 500 traditional Gap stores and 300 outlet units.

There is also speculation that the company could sell off Old Navy and/or Banana Republic to generate cash. Last year it shut down its Piperlime women’s wear brand.

Sales per square foot at the Gap chain have dropped to $361 last year from $376 in 2007.