\begin{table}[htbp]\centering
\caption{Robust IV Estimates of Log Registrations on Log Highway Gas Use \label{tab:GasUseiv}}
\begin{tabular}{l*{4}{c}}
\hline \hline \multicolumn{5}{l}{\textit{Panel A: IV Estimates and Robust 95\% Confidence Intervals}} \\&            &            &            &            \\
\multicolumn{5}{c}{Dep. Var.: Log Number of Vehicle Registrations} \\ &         (1)&         (2)&         (3)&         (4)\\
$\gamma$    &      -0.420&       -0.47&       -0.67&       -0.64\\
95\% Conf. Set&[-1.75, 0.27]&[-1.71, 0.33]&\makecell{(-$\infty$, $0.23]$; \nextline $[8.59$, $\infty$)}&\makecell{(-$\infty$, $0.32]$; \nextline $[2.85$, $\infty$)}\\
\makecell[l]{Data Source \nextline Controls}&        None&  Documented&\makecell{Large \nextline Undocumented}&\makecell{Small \nextline Undocumented}\\
State Fixed Effects&           Y&           Y&           Y&           Y\\
Year Fixed Effects&           Y&           Y&           Y&           Y\\
\makecell[l]{State-Specific Linear \\ Time Trends}&           Y&           Y&           Y&           Y\\
Common Controls&           Y&           Y&           Y&           Y\\
Number of Obs.&       2,429&       2,429&       2,429&       2,429\\
\hline \hline \multicolumn{5}{l}{\textit{Panel B: Anderson-Robin Test Statistics and P-Values}} \\&            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=11$}} \\ AR Stat&     5.877**&     6.042**&      3.718*&      2.806*\\
p-value     &       0.015&       0.014&       0.054&       0.094\\
            &            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=9.7$}} \\ AR Stat&     5.892**&     6.052**&      3.777*&      2.856*\\
p-value     &       0.015&       0.014&       0.052&       0.091\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$1}} \\ AR Stat&     5.707**&     5.462**&     6.062**&     5.266**\\
p-value     &       0.017&       0.019&       0.014&       0.022\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-4.8}} \\ AR Stat&     5.237**&     5.479**&       2.284&       1.673\\
p-value     &       0.022&       0.019&       0.131&       0.196\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-6.1}} \\ AR Stat&     5.365**&     5.606**&       2.486&       1.825\\
p-value     &       0.021&       0.018&       0.115&       0.177\\
\hline \hline \end{tabular} \vspace{0.2cm} \begin{tablenotes} \begin{spacing}{0} \begin{footnotesize} \item \textbf{Notes:} The top panel of this table presents IV estimates and 95\% confidence sets robust to weak instruments of the linear relationship between log highway gas use and log vehicle registrations.  The bottom panel presents Anderson-Rubin chi-squared statistics along with p-values for different null hypotheses pertaining to the parameter estimated in the top panel. The unit of observation is state-year. The four specifications pertaining to different levels of  (DSCs) and control specifications are documented in Table \cref{ssec:Spec}. Confidence sets are based on standard errors clustered by state. * p\textless 0.1, ** p\textless 0.05, *** p\textless 0.01 \end{footnotesize} \end{spacing} \end{tablenotes} \end{table}
