Back in the 1900s, some stop signs were yellow because it was too hard to see a red sign in a poorly lit area.

早在20世纪初，一些停车标志是黄色的，因为在光线不好的地方很难看到红色标志。

youdao

We were staying in a seedy hotel close to the red light district.

我们住在靠近红灯区的一家脏乱的旅馆里。

《柯林斯英汉双解大词典》

London cares about them even more, because the red booths have long been a special scene in London since the 1930s when they were painted all red.

伦敦更关心它们，因为从20世纪30年代起，红色电话亭就一直是伦敦的一个特殊场景，当时它们都被漆成红色。

youdao

In the past, numbers in the financial records of a company were written in red ink to show a loss.

VOA: special.2009.04.26

A damaged table, 3 chairs and an old red sofa were in the center of the floor.

VOA: special.2009.01.17

A damaged table, three chairs and an old red sofa were in the center of the floor.

VOA: special.2010.06.12

By 1:37 PM in New York, all three major equity indices were in the red.

FORBES: 5% Upside For Equities Despite 'Austerity Fatigue' Hitting Global Markets

Property and casualty insurers like Allstate, Progressive and Travelers were in the red.

FORBES: Stocks Wobble After Sandy, Knight Capital Dealing With Outage

Markets were in the red for the majority of trading Wednesday, but bounced back and moved near positive territory later in the day.

FORBES: Why More QE Isn't Coming