This chart shows the top five venture capital regions in the US, with the total venture capital investment in the period 2003-2007. Note that it compares Silicon Valley (just one of several California regions) with all of New England. If the analysis is narrowed to Massachusetts vs. Silicon Valley, the trend is the roughly same. The sums on the Y axis represent total venture capital in each region, for all industries at all stages. This chart was compiled in 2008 based on PricewaterhouseCoopers MoneyTree survey data. The raw data is available here:
A quick glass at the latest year's data appears to continue this trend.