"color line" meaning in English

{
  "forms": [
    {
      "form": "color lines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "color line (plural color lines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2006, Matt Wray, Not Quite White, page 82:",
          "text": "Antimiscegenation laws were directed primarily at people of color and at low-status, disreputable whites, the poor white trash who refused to uphold the color line.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Synonym of colour bar"
      ],
      "id": "en-color_line-en-noun-5bAPajhb",
      "links": [
        [
          "colour bar",
          "colour bar#English"
        ]
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "colour bar"
        }
      ]
    }
  ],
  "word": "color line"
}

{
  "forms": [
    {
      "form": "color lines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "color line (plural color lines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "examples": [
        {
          "ref": "2006, Matt Wray, Not Quite White, page 82:",
          "text": "Antimiscegenation laws were directed primarily at people of color and at low-status, disreputable whites, the poor white trash who refused to uphold the color line.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Synonym of colour bar"
      ],
      "links": [
        [
          "colour bar",
          "colour bar#English"
        ]
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "colour bar"
        }
      ]
    }
  ],
  "word": "color line"
}