An honors thesis involves substantially more work that than a term paper. It will probably be the largest single project you will undertake as an undergraduate. A library research thesis is usually 25 to 35 pages long. It necessarily involves multiple rounds of revisions. It can be done in one full semester if the topic and scope are clearly laid out before the semester starts, but two semesters are recommended.
Empirical research takes time to design, analyze, and write up.
In the past, some students who tried to complete an empirical research thesis in one semester ended up postponing graduation another semester. The analysis and write-up of archival data may be possible in one semester. Find a Faculty Sponsor who is willing to supervisor your work. At the very latest, you must have a sponsor by the beginning of the semester you plan to graduate. You may need to talk to several faculty members before you find one who has the time and interest required to supervise your thesis.