The Delta Conjecture at $q=1$

We use a weight-preserving, sign-reversing involution to find a combinatorial expansion of ${\mathrm{\Delta }}_{e_k}{e}_n$ at $q=1$ in terms of the elementary symmetric function basis. We then use a weight-preserving bijection to prove the Delta Conjecture at $q=1$. The method of proof provides a variety of structures which can compute the inner product of ${\mathrm{\Delta }}_{e_k}{e}_n{\mathrm{\mid }}_{q=1}$ with any symmetric function.