Denote by ${\mathfrak s}({\mathbb F}_p^d)$ the Erd{\H o}s--Ginzburg--Ziv constant of ${\mathbb F}_p^d$, that is, the minimum $s$ such that any sequence of $s$ vectors in ${\mathbb F}_p^d$ contains $p$ vectors whose sum is zero. Let ${\mathfrak w}({\mathbb F}_p^d)$ be the maximum size of a sequence of vectors $v_1, \ldots, v_s \in {\mathbb F}_p^d$ such that for any integers $α_1, \ldots, α_s \ge 0$ with sum $p$ we have $α_1 v_1 + \ldots + α_s v_s \neq 0$ unless $α_i = p$ for some $i$. In 1995, Alon--Dubiner proved that ${\mathfrak s}(\mathbb F_p^d)$ grows linearly in $p$ when $d$ is fixed. In this work, we determine the constant of linearity: for fixed $d$ and growing $p$ we show that ${\mathfrak s}({\mathbb F}_p^d) \sim {\mathfrak w}({\mathbb F}_p^d) p$. Furthermore, for any $p$ and $d$ we show that ${\mathfrak w}({\mathbb F}_p^d) \le {2d-1 \choose d}+1$. In particular, ${\mathfrak s}({\mathbb F}_p^d) \le 4^d p$ for all sufficiently large $p$ and fixed $d$.