Permit extensions allow OSOW carriers to prolong the number of days a permit is valid. Some states issue an extension on a single trip permit, but some require the carrier to refile the permit. The permit extension process can be much quicker than refiling a permit. Refiling a permit may require the carrier to start the application process over behind all new permits, whereas an extension progresses quicker because it is not a new permit subject to the scrutiny and analysis required for new permits. The number of days that a permit could be extended and the reasons for the extension vary between states. Many states reported that extensions were issued on a case-by-case basis, with weather and mechanical problems being the most-cited reason for granting an extension. When a state responded that it allowed extensions on a case-by-case basis, the research team classified them as allowing extensions.