As they have for recent fall semesters, two of Harvard’s flagship undergraduate classes—one in computer science and the other in economics—are vying for the position of the College’s largest fall course.

As of Sunday evening, Economics 10a: “Principles of Economics” had enrolled just barely more undergraduates than Computer Science 50: “Introduction to Computer Science I” with 701 undergraduates compared to 697, respectively. By this point last fall, CS50 had surpassed the economics course in enrollment, breaking a record.

In terms of overall course enrollment numbers—which count student enrollees hailing from the Graduate School of the Arts and Sciences, cross-registered programs, and elsewhere—CS50 outnumbers Ec 10 by nearly 100 students: 804 total students, compared to 707. CS50’s continued success in drawing hundreds of students comes on the heels of the program’s continued presence online and its recent expansion to Yale.{shortcode-2f30af357e0c200b99e10142a57bd9e6739215aa}

Famous Government professor Michael J. Sandel’s General Education course Ethical Reasoning 39: “Money, Markets, and Morals” has the third largest undergraduate enrollment, with 514 College students enrolled as of Sunday evening. And Life Sciences 1a: “An Integrated Introduction to the Life Sciences: Chemistry, Molecular Biology, and Cell Biology” was the College’s fourth largest class, also as of Sunday evening, with 431 undergraduates enrolled.

Students enrolled in courses online for the first time this year, through the recently overhauled my.harvard website. It tabulated enrollment numbers, a departure from last year, when the Faculty of Arts and Sciences Registrar collected paper study cards, FAS Registrar Michael P. Burke said. The data, this semester and going forward with the site, collect in real time.

“[W]e have actual enrollments,” Burke said. “And we have had actual enrollments since Sept. 2.”

From that date through the study card submission deadline last Thursday, when students enrolled in a course, faculty members could see students’ names as they appeared on their rosters.

“There [was] a lot of traffic every day,” Burke said. “Everything about our work is entirely new, and we’re experiencing it for the first time just like students and everybody else.”

Add/drop period, when students can change their course schedules, starts this week and continues through Sept. 21. After that date, students will be charged a fee for enrolling in new courses or dropping old ones from their schedules.

Until then, it is remains to be seen whether CS50 will edge out Ec 10.