This research attempted to reveal the existence of digital divides, their relationships to users' socio-demographics, and the Internet adoption and usage patterns. It was a longitudinal investigation targeted to the adults eighteen years or older in the household setting from the nation-wide surveys conducted in the United States between 2000 and 2010. Digital divides were investigated in three levels (dimensions): Internet access, usage (frequency), and scope (consequence). Six socio-demographic characteristics were investigated: gender, age, education, income, occupation, and race. This research showed that Internet access rates and usage increased consistently from 2000 to 2010. However, the disparities in the Internet adoption and usage among the diverse Internet users were still observed. Gaps by age, education, income, and occupation were ubiquitously prominent except for gender and race; little difference was found between men and women for Internet access and between whites and African-Americans for Internet usage and scope. The evolution of the digital divides in Internet usage and scope were complicated because some gaps closed or opened periodically from 2000 to 2010. This research showed that Internet access rate and usage were negatively related to age but positively related to education and family income. The poorest, least educated, old or least privileged people still lagged behind in Internet access, usage, and scope. It is too early to declare the battle against the digital divides won. The findings of this research call for further education and training for the laggards to narrow the existing gaps. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]