Over the past three to four decades much has been accomplished with regard to improving the noise environment in the United States, and there are many new technologies and approaches that offer the possibility of further improvements. Continued research in the area of transportation-related noise abatement is necessary to ensure that past accomplishments can be realized in the future. This background paper presents a brief historical perspective of past milestones in transportation-related noise control, along with a discussion of the more substantial ongoing activities. It provides information for policymakers as they endeavor to determine how best to allocate continuously shrinking research funds. It also provides researchers with some thoughts regarding novel research areas for the future. For convenience, the three primary modal areas--aircraft, highway, and rail--are discussed separately. Recognizing that this is not only an era of shrinking research dollars, but a time in which transportation planning is increasingly involved on a cross-modal level, this paper also briefly discusses the need for resource sharing among different transportation agencies.