The Columbus Dispatch reports that the total number of pages of briefs submitted (including Amicus Briefs) in the same-sex marriage cases the US Supreme Court will consider April 28 is over 7,500. That's a lot.
Is this the most number of pages ever? No. "Court observers say the volume of filings in the case, combined under the heading of Obergefell v. Hodges, is second in recent memory only to the 2012 Affordable Care Act case in which President Barack Obama’s health-care plan was eventually upheld by a divided Supreme Court."
Isn't there a page limit on briefs? Sort of. The limit is actually a word limit per Supreme Court Rule 33. Merit briefs are limited to 15,000 words.
Where do you get all of these briefs if you'd like to brush up before arguments next week? SCOTUS Blog has the various briefs. Amicus briefs are limited to 9,000 words. For comparison, a 28-page law review article has around 15,000 words. So, based on the calculation that there are over 7,500 pages to read, it sounds as though there are around 260 briefs.
Didn't I read over 7,500 pages in my first year of law school? Maybe. In the 1L year, students take 31 hours of class over 28 weeks. (Let's say 15 hours are in the first semester and 16 are in the second.) If a professor assigns an average of 20 pages per hour, that means students read approximately 4200 pages in the first semester (300/week*14 weeks) and 4480 pages in the second semester (320/week*14 weeks), you're well on your way to a successful Supreme Court clerkship, if only in terms of the reading requirement.