A Garland for May Day was used as the cover design for the Clarion in 1895 (May issue, of course).
The idea of solidarity is portrayed in the poster above. It presents all workers of the world holding each other's hands and dancing around the globe. Names of all continents are incorporated in the picture, just like we could expect from a master of illustration and design.
This cartoon from 1907 not only celebrates the idea of socialism but puts a woman in the first plan. The organized fight for women's rights started in the late 19th century and was already pretty loud at the beginning of the 20th century when Crane created the illustration above. He strongly supported the idea of equality and made his own contribution to the suffrage movement.
The Workers' May Pole is one of the most typical Crane's works. People of both genders dance around the goddess with a banner (Socialism, Solidarity, Humanity). The goddess acts like a May Pole and is covered with long strips. Each one of them presents one of the mottos like 'Life worth living', 'The land for the people', Abolition of privilege, Employers' liability', 'Leisure for all', etc.
On the other hand, Crane still kept working on illustrating books for children although he created less than before. Here are a few way more playful and colorful takes on the same subject:
Come Lasses & Lads is an old song about the celebration of the beginning of May with a pole dance.
Twas in the Merry Month of May is one of the songs in the book Pan-Pipes A Book of Old Songs Newly Arranged and with Accompaniment. Both illustrations above can work great as parts of printable May calendars.