\documentstyle[12pt]{article}
\begin{document}
\section{United States}
\subsection{California}
\subsubsection{Earthquakes}
\subsubsection{Floods}
\subsubsection{Fires}
\subsection{Texas}
\subsubsection{Wide Open Spaces}
\subsubsection{Hot Weather}
\subsection{New York}
\subsubsection{Cold Winters}
\subsubsection{Rain}
\section{United Kingdom}
\end{document}
Notice that the spacing had no effect on the resulting output.