This report outlines LTPP’s 2004 program area accomplishments and how the TEA-21extension impacted the LTPP program. Highways are the backbone of our Nation’s transportation system. They play a vital role in the Nation’s economy as well. In 2004, the Long-Term Pavement Performance (LTPP) program continued working toward optimizing the public’s investment in the highway system by providing the information, data, and products that highway engineers and managers need to design, build, maintain, and manage cost-effective and better performing roads.