The longest sentence I have ever read, till now, contains 73 words. :

"The whole region was sparsely settled by people of the frontier--restless souls who no sooner had hewn fairly habitable homes out of the wilderness and attained to that degree of prosperity which today we should call indigence, than, impelled by some mysterious impulse of their nature, they abandoned all and pushed farther westward, to encounter new perils and privations in the effort to regain the meager comforts which they had voluntarily renounced."

But the longest sentence as far as i know contains more that 1,000 words.