From The Vault

As the NCR Rangers are a threat to slaver operations in Northern California, they would do anything to hamper their operations. The slaver Vortis from NCR looks to procure the Ranger Map from their headquarters in the downtown NCR area and the Chosen One can provide him with it, for adequate compensation.

While in vanilla Fallout 2 nothing follows, in killap's Fallout 2 Restoration Pack, which includes Ranger Safehouses scatter across Northern California, you will find dead Rangers at these locations, as Slavers subsequently raid them.