We expand on Tutte's theory of $3$-blocks for  $2$-connected graphs, generalizing it to apply to infinite, locally finite graphs, and giving necessary and sufficient  conditions for a labeled tree to be the $3$-block tree of a  $2$-connected graph.
['Carl Droms', 'Brigitte Servatius', 'Herman Servatius']
The Structure of Locally Finite Two-Connected Graphs