Overnight parking in Walmart parking lots is popular among RVers. Walmart’s official policy is to allow RVers to park overnight where they are able. Permission to park overnight is granted by individual store managers, based on availability of parking space and local laws. But there are more than 800 Walmart stores nationwide where overnight RV parking is prohibited. That’s about 20 percent of all Walmart and Walmart Supercenter stores in the United States. A free Walmart RV Parking Directory is available for download. The directory lists stores where overnight RV parking is not allowed.