The Wednesday prior to the start of a holiday weekend produced lower-than-usual scores for veteran reality series “Big Brother” and “So You Think You Can Dance,” though the former remained the night’s top program in demos. Reversing the trend was NBC’s new drama “Taxi Brooklyn,” which edged up in its second week.

According to preliminary national estimates from Nielsen, “Big Brother” averaged a 1.8 rating/7 share in adults 18-49 and 5.6 million viewers overall during the 8 o’clock hour, standing as the night’s top show in 18-49 and 25-54 (2.2/7). Though down half a ratings point from its season premiere of last Wednesday, it was up a tenth from its comparable night of a year ago (which was the night before Independence Day); it also did a 1.8 with its first Sunday episode of this season.

CBS followed “Big Brother” with an encore of the second-season premiere of Monday’s “Under the Dome” (0.6/2 in 18-49, 3.3 million viewers overall) and a repeat of “CSI” (0.7/3 in 18-49, 4.5 million viewers overall).

At NBC, which tied with Fox for the night’s top 18-49 average while also winning in total viewers, “Taxi Brooklyn” (1.1/4 in 18-49, 5.4 million viewers overall) became the first new scripted series of the summer on broadcast or cable to match or build upon its premiere score in 18-49. (Fox’s “Gang Related,” which bowed before Memorial Day, also achieved it in its second week, rising from a 0.9 to a 1.0 in the demo.) Airing opposite a repeat of ABC’s “Motive” this week, “Taxi Brooklyn” was up a tenth in the prelims and also in line with last week in total viewers.

“Taxi Brooklyn” followed a two-hour repeat of “America’s Got Talent” (1.4/5 in 18-49, 6.3 million viewers overall), which beat out the 200th episode of Fox’s “So You Think You Can Dance” (1.3/5 in 18-49, 4.0 million viewers overall), which was down a tenth from last week and matched its low.

Univision, which ranked third Wednesday in 18-49, had the night’s top scripted program with “Lo Que la Vida Me Robo” at 9 (1.5/5 in 18-49, 3.7 million viewers overall).

ABC aired repeats of comedies “The Middle” (0.9/4 in 18-49, 3.9 million viewers overall), “The Goldbergs” (0.8/3 in 18-49, 3.2 million viewers overall), “Modern Family” (1.0/4 in 18-49, 3.5 million viewers overall) and a second “Goldbergs” (0.9/3 in 18-49, 3.1 million viewers overall). A repeat “Motive” closed the night (0.6/2 in 18-49, 2.4 million viewers overall), with the show back in originals next week.

CW aired repeats of “Arrow” (0.2/1 in 18-49, 0.9 million viewers overall) and “The 100” (0.2/1 in 18-49, 0.7 million viewers overall).

Preliminary 18-49 averages for the night: NBC and Fox, 1.3/5; Univision, 1.2/4; CBS, 1.0/4; ABC, 0.8/3; Telemundo, 0.7/2; CW, 0.2/1.

In total viewers: NBC, 6.0 million; CBS, 4.5 million; Fox, 4.0 million; ABC and Univision, 3.1 million; Telemundo, 1.6 million; CW, 0.8 million.