We conducted a longitidinal assessment of 806 respondents in March, 2020 in the US to examine the trustworthiness of sources of information about COVID-19. Respondents were recontacted after four months. Information sources included mainstream media, state health departments, the CDC, the White House, and a well-known university. We also examined how demographics, political partisanship, and skepticism about COVID-19 were associated with the perceived trustworthiness of information sources and decreased trustworthiness over time. At baseline, the majority of respondants reported high trust in COVID-19 information from state health departments (75.6%), the CDC (80.9%), and a university (Johns Hopkins, 81.1%). Mainstream media was trusted by less than half the respondents (41.2%), and the White House was the least trusted source (30.9%). At the 4-month follow-up, a significant decrease in trustworthiness in all five sources of COVID-19 information was observed. The most pronounced reductions were from the CDC and the White House. In multivariate analyses, factors associated with rating the CDC, state health department, and a university as trustworthy sources of COVID-19 information were political party affiliation, level of education, and skepticism about COVID-19. The most consistent predictor of decreased trust was political party affiliation, with Democrats as compared to Republicans less likely to report decreased trust across all sources.