Emily uses the color purple in many of her poems. The use of the color purple represents different things according to the imagery it relates to in each poem individually.
The color purple can represent many different things. Historically, the color purple can represent perfect balance given it is a combination of red (the warmest color) and blue (the coolest color). It is also representative of mourning. Another way the color is used is as a representative of the coming of spring. One last use of the color purple denotes royalty.
For Dickinson's poem "One dignity delays for all", the color purple represents royalty.
One dignity delays for all--/ One mitred afternoon--/None can avoid this purple--/ None can evade this crown.
The word mitre refers to the headdress worn by bishops. The second line makes a more direct referral to royalty ("crown").
The entire poem speaks to the passing of royalty, a bishop, and the entourage. The speaker, a simple person, states that he/she has no other choice but to join the bishop or die.