There are no Fees collected by the National Park Service to visit the Mormon Pioneer National Historic Trail. However, other federal and state agencies may have Recreation and Use fees that are collected for managed resources and lands. Many of the private museums and interpretive centers along the trail may also have fees. You should inquire locally about these.
The Links and Resources page includes contact information for many of the interpretive centers and land agencies that manage trail resources. It also list a bibliography of suggested books and resources that may be useful as well.
Information about purchasing the National Park Golden Eagle & Parks annual passes, the lifetime Golden Age and Access passes (now called the America the Beautiful Passes) is available here. There are no fees for visiting the national historic trails, but some trail resources and sites are on federal lands managed by other agencies that do collect these fees.
Although administered by the National Park Service, the Trail is not a traditional National Park area with campgrounds, lodges and borders. Reservations for camping and lodging may be available in many areas, but you will need to contact the local land managing agency or property owner. Sometimes reservations may be available for guided tours and interpretive programs at Trail sites. Again, inquire locally with the site manager for this information.
Information for suggested sites to visit, along with driving directions, may be found on the Things to Do web page.