Parents who paid $200 for a newsletter written by a local admission consultant, Elissa Stein, got reminders about that and other aspects of the application process, Ms. Shapiro reported.

One parent toward the front of the line, Jill Taddeo, said, “The Department of Education should be doing what Elissa Stein is doing, for free.” (A spokeswoman for the department said consultants had a financial incentive to raise concern about the admissions process.)

The lines that surround Beacon and other elite high schools “are a living symbol of the anxiety, competition and inequality that define New York’s segregated public school system,” Ms. Shapiro wrote.

What the line tells us about the city’s high schools

“The fact that parents are paying $200 for a newsletter that gives them information about the process tells us a lot about how difficult this process is to navigate for pretty much everyone,” Ms. Shapiro said.

For years, students could simply attend their local high school. That changed in 2003, when Mayor Michael R. Bloomberg got rid of the zoned high school system . The rules in place today allow students to apply to up to 12 high schools anywhere in New York City; then an algorithm matches them with one school.

The goal of the current system is to give students who live in neighborhoods with underperforming high schools a chance to attend better ones. The changes helped create a lucrative marketplace for education information. And parents who can more easily gain access to that information — When is Beacon’s open house? When do I have to register for it? — have an advantage.

“I think choice as a concept is really appealing and makes a lot of sense, and parents did want it,” Ms. Shapiro said. “But it creates haves and have-nots.”